bullet bases

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Ross Smith posted this 10 December 2019

After reading a little by Dr. Mann and Harry Pope about bullet bases it brought back some of my worries about bullet bases. Not just Pope and Mann, but several experts have stated the bullets base to be the most important part. They were even arguing that the small amount of lead displaced by the lands causing small fins on the edge of the bullets base to alter the point of impact. Now these guys were probably concerned about .01" or less which is enough to win some matches. But how does that effect us mortals?

I've often wondered about gas checks that don't go on straight. Not just the really ugly ones but also the ones you need a small square to see the the bullet tip when stood on its base. While I was lube sizing several hundred noe 165gr fp bullets and not really trying for match quality bullets , I was getting quite a few crooked gas checks, some would not even stay on the bullet. So the light bulb flashed on. I sorted out 10 really bad ones, the ones you recycle into the pot. Some of these would not even stand up. Very crooked. Then I got out my small machinist square and sorted thru the bullets to come up with 10 that were very square to the world. These 2 groups were loaded over 20 gr R7(my load my fingers) in 30-06 mixed headstamp cases. I also took 10 30-06 cases loaded the same but with noe xcb bullets, my normal load. The xcb were my control and the other 2 groups were the experiment. The xcb went inot 2" out of a cold barrel. ED's red wiped thru the barrel then shot my 10 good 30-30 fn bullets. 4". I didn't expect much and was actually pleased with 4", after all no load developement. Next came the really bad bullets, 4". No effect, at leasdt in this under funded experiment. So ther goes my excuse for those wild fliers that miss the whole target.

What say you all?

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Tom G posted this 11 December 2019

Ross, 

Out of square bullet base will definitely cause fliers. But not fliers that will miss the target. About 6 or 8 yrs. ago I decided to find a good cast bullet load that would shoot in my AR-15 house and bug-out gun. I shot hard water dropped bullets and had a load that shot an average of 1.25" at a hundred yards.  I tested it against a load made up of jacketed FMJ bullet that were just blasting quality and fairly cheap. The cast load beat out the jacketed load. by a small amount. 

Later, my brother decided to work up a cast load for his AR and eventually sent me some bullets he had cast and shot in his gun. I shot them in my gun and got unexplained fliers. They maybe doubled or tripled the group size. They were in the range of 4 inch groups.  I got to looking at his bullets and when sitting them up on their bases, I could see the gas checks were  on slightly crooked. They definitely caused fliers.  

Perhaps your groups are so large at 4" that the fliers don't make them any larger than the groups without fliers. Maybe if you worked up a load that was accurate, you would see the difference. Following Dr, Mann's lead, you might try taking the crooked gas check bullets and orienting them in the chamber so that the out of squareness was in the same direction for all the bullets. Maybe they would shoot to a group!! Seems to me that Mann did the same type test with plain base bullets.   

When I was shooting CBA benchrest, I always bumped my bullets in a bump press. This was for two reasons. First to make the bullet the exact same shape as the tapered chamber throat in the gun and make the rear driving band a couple of tenths larger so I would have slight interferance fit when I chambered them. This also formed the gas check flat and square on the bullet. Having a friend who was a tool and die maker, I had him take a couple to work with him and measure the base squareness on an optical comparator. He reported back that the samples that I had bumped were "dead nuts Square". These bullets would routinely shoot around  a half inch at 2500 fps. Knowing that the edge of the gas check was a critical factor to accuracy, I bumped them just hard enough to flatten the base but not remove the round edge of the gas check. These were tapered bullets seated into a tapered throat. 

My bump press was adjustable for the amount of bump and had an ejector built into it. The bump die was made from the same throater reamer that I used to throat the chamber throat in the gun. I purposely designed the throater to make a .309 throat diameter into a half degree per side taper on the lands. Thus the bullet fit the throat like a morse taper. It also sealed in the back end to stop any gas from flowing past the bullet and damaging the bullet or knocking the lube off the bullet. Bumped bullets were .3093" into a .3090" throat. and were seated way long with just the base of the bullet in the case neck. This allowed the bullets to be oriented straight to the rifling because the chamber throat held the bullet straight and hot the case neck. 

One of my deceased prairie dog shooting buddies was a retired scientific type. His I Q was measured over 165. At one time he worked on and off a bunch of government projects. One was to develop a nuculear artilliary shell. The shell had a nuclear warhead and had a rocket motor attached to the base of the projectile. The rocket motor was timed to fire off near the top of the trajectory curve and propel it about 5 times further than normal. This shell had serious accuracy problems. As a result they determined that the edge of the base of the shell was being eroded by the rocket blast. The fix was to implant a ceramic ring to form the edge of the base of the bullet and hold up to the heat generated by the rocket blast. It shot accurately when they did that. 

Tom G. 

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Squid Boy posted this 11 December 2019

I use a lot of M198 duplex ammo and even some experimental quad bullet stuff while in the Army. Both had angles built into the last bullet in the stack. I believe the angle was 4% and it opened that last bullet so as to hit about 10 inches off center. It seemed like a good idea but the individual bullets were pretty light and easily deflected. I would say your results are unusual and there could be other factors at play. My experience is the better the base, the better the shooting. Thanks, Squid Boy

"Squid Pro Quo"

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Ross Smith posted this 11 December 2019

I agree and like  the posts. I purposely made sure that I was not trying for "match" ammo. Just wanted run of the mill plinker stuff and I will see if I can refine this load for my '03. It doesn't like the xcb but did shoot "ok" with the flat nose. The other thing being that the flat nose mould is a 4 chamber mold and can spit out a lot of bullets. From now on for my plinkers I won't worry about sorta off kilter gc's but the ugly ones will still go back in the pot. 

If I remember right it was Mann or someone like him that said the gap in front of the gc collected the displaced lead and increased accurracy over pb's. However the pb breach seaters sure do shoot small groups. Which brings me back to long slow bullets in slow twist barrels........my other bug-a-boo....rifling twist rate.

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John Alexander posted this 11 December 2019

Ross asks -- "What say you all?

I say congratulations on running a nifty, although limed, experiment challenging one of the hoary old cast bullet axioms that most cast bullets shooters swallow whole with never a doubt.  Being skeptical is the only way we will ever learn anything.

You found that even with horrendously crooked bases (some wouldn't stand on their bases) the groups were the same as the bullets with good bases.  This isn't what we have been told to expect. True, the test was small and the results doesn't say much about what the results would have been if the perfect bases had shot much smaller groups.  I assume you were shooting at 100 yards and that level of accuracy, or larger, is often mentioned in TFS articles and not unreasonable for many uses. 

I have run a lot of comparison test between "perfect" base bullets and bullet with base defects and have been surprised at the lack of dramatic accuracy loss easily seen defects or slightly skewed based cause. 

So far I have not been able to show that gas checked bullets with rounded bases or small wrinkles in the base reduce accuracy at all in five shot groups that average 1" 

I have also found bases skewed up to 2 degrees (easily seen) increased my groups from average of .96" to 1.28".  1.28" not good to win many CBA matches but still good enough for any practical use. This test was written up in Fouling Shot 212, July/August 2011. I would be happy to send a copy to anybody curious enough to send me their email address.

Keep on experimenting Ross.

John

 

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RicinYakima posted this 11 December 2019

John wrote; "I have also found bases skewed up to 2 degrees (easily seen) increased my groups from average of .96" to 1.28".  1.28" not good to win many CBA matches but still good enough for any practical use."

And that is the crux of the issue, for me. When I am prepping for a 120 round match I make about 200 bullets. When all finished the VISUAL best 120 go into the match boxes, but the others are foulers (well barrel warmers) and sighters. Foulers go into the dirt, but the sighters will almost always go into the group so are used for sight changes.

Making bullets for the 30/40 for walks in the sage brush to shoot varmints, vermin and rock buffaloes, don't get much of an inspection, because it is hit or miss. Part of the adventure is having bullets I made myself to shoot, but another is making the "best" that it is possible to make. John has convinced me that much of the OCD things I do for match bullets is just to make me feel good, and is seldom seen on the targets.

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BigMan54 posted this 12 December 2019

Before the Saeco Lubi-Sizer with swing out gas check seater. And the Lyman attachment for their's and RCBS.

My Dad used a "coin slug" over the top of the size die to seat gas Checks on straight. 

Don't need the slug these days but I've always seated my gaschecks on straight with the gascheck seater.

If the straight on gaschecks worked for Dad, that's good enough for me. 

And It's proved itself to me shot after shot. 

I REALLY HATE AUTO-CORRECT 

 

Long time Caster/Reloader, Getting back into it after almost 10yrs. Life Member NRA 40+yrs, Life S.A.S.S. #375. Does this mean a description of me as a fumble-fingered knuckle-draggin' baboon. I also drool in my sleep. I firmly believe that true happiness is a warm gun. Did I mention how much I HATE auto-correct on this blasted tablet.

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Squid Boy posted this 12 December 2019

I think one of the more interesting aspects of Mann's tests was that purposely damaged bullets shot well when oriented to exit the muzzle in the same position on every shot. That is, bullets with the same obliqueness or off balance condition shot well. Mixed problems produced fliers regardless of orientation. I find in my own testing that once you get down to very small groups, everything makes a difference down to what seems like an immaterial thing when striving for the absolute minimum group size. You will occasionally shoot a fantastic group with mediocre bullets due to a happy coincidence but it won't happen often. Kicking new ideas around and challenging the old ones is what makes cast bullets so interesting to me and I am a new comer to this. My humble opinion only. Thanks, Squid 

"Squid Pro Quo"

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Dale53 posted this 12 December 2019

Due to vision problems, I no longer compete in cast bullet matches. However, since it is relatively easy to produce near perfect bullets, why would I want to cast imperfect ones? When using gas checks, I simply used a gas check seater to make sure they were seated perfectly. Easy-peasy!

These comments can be taken as confrontational. That is not intended at all. What I would like to do is to simply encourage anyone who is casting bullets to set high standards for themselves, and often with a change in attitude, comes near perfection!

The act of positive thinking...

FWIW

Dale53

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Ken Campbell Iowa posted this 12 December 2019

about " square " bases ...  back when i was trying to get my sporter rifles under 2 moa with cast, ..... having tortured my way through Mann's book a couple times ...  and read a few articles on Pope and even got to,play with a Pope 32-40 muzzle starter system ( with Pope mold )  , remembering the trouble he took to have a fitted bullet and his comments on bases ...

having determined that the first rule ( bullet snug in the throat ) was to be obeyed first thing ...

i fantasized that the base was the magic key to the last 1 moa ... so i dedicated ~800 rounds of pretty good castings with and without lathe collet turning the bases .. the idea was that would be the only difference in fit and basic form ..... Joeb is right,  ::  800 ain't enough cool ... but there was a strong hint that better bases shoot better ...  normalized bases gave me the only 10 shot groups under 1 moa with sporter rifles.   but the magic trick failed to turn my pretty good castings into under-1.5 moa consistently ...   btw, i used commercial all Taracorp Magnum alloy, not hardened.  great stuff.

interesting that half the bases were turned 90 degrees flat ... and half were turned with a large bevel base ... both shot the same ...   yes, all used the old lyman checks ... even the bevel based ones ... you would think those would distort unevenly and groups would enlarge... but they didn't seem to be worse.

also through those guns with the same starter castings, i made several swagers ... mainly to square the base y checks ..  and they also showed slight improvement .. but of course the whole bullet was re-formed during the swaging, so several variables were changed.

the above was through factory sporter barrels, even 2 moa  cast groups required some load development, and a bit of luck.   those factory sporters would shoot under 1 moa with mj bullets.

and yes lathe turning bases is tedious ... but you can try different cuts on different bullets.   the squisher tool is a better answer once you determine what works. 

*************

so today for my plinking level loads, i cast scrap, obey rule 1 ( snug in the throat ) and visibly check and remelt any terrible base castings ... the nose is much less critical   ...  no gas check and about 1100-1300 fps... i expect a max of 3 moa for plinking and can usually get there ... eventually . 

if i were shooting group competition, i would definitely normalize the bases.

ken

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Ross Smith posted this 12 December 2019

Next I'm gonna load up some of the wrinkled pitted ugly poured to cold dirty mold bullets. Of course I'll use 10 just so I have a statistical sample.

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max503 posted this 13 December 2019

I've often wondered if the pressure of firing would seat a crooked gas check.

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RicinYakima posted this 13 December 2019

max503, me too. I would think it would an Ideal slip on, but wonder about crimp on ones?

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45 2.1 posted this 13 December 2019

I've often wondered if the pressure of firing would seat a crooked gas check.
Indeed it does. Tests involving intentionally crooked seated Hornady gas checks show a raised portion of lead above the gas check on the part that isn't fully seated on the bullet shank. All recovered bullets in the tests showed this and all gas checks were flat on the bullet base.

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John Alexander posted this 13 December 2019

Ric,

Remember that Dan Lynch showed either in a Fouling Shot article or in a post to the forum that the thickened rim in advertisement for Hornady gas checks doesn't exist on his sectioned gas check.  So maybe it doesn't crimp as solidly and thus 45 2.1,s observations.

This may be the reason why the skewed gas checks shoot better than they outa.

John

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RicinYakima posted this 13 December 2019

John, After I saw that, I looked a lot of about 10 Hornady .30 gas checks. They are not like the illustrations, but appear to be the sheared metal from the punching process. But I have no guess as to how strong they would be. I am glad 45 2.1 added his experience on this topic. Ric

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45 2.1 posted this 13 December 2019

.  So maybe it doesn't crimp as solidly and thus 45 2.1,s observations.
Once ran thru the sizer in a tilted condition, those Hornady checks take excessive force to move using the lubrisizer. Try taking one off and it's a job. The starting force from the primer is about 2,000 PSI and it does move a tilted GC... of course you usually have to knock the bullet out of the rifling to see that. In all my testing it seems the GC is seated flat before it reaches the rifling.

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Ross Smith posted this 13 December 2019

HMMMMMMMMMMMMM

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Tom Acheson posted this 13 December 2019

Unless I missed it, this discussion is focused on bullets that will eventually have gas checks applied to them.

The guys who shoot Black Powder Cartridge Rifles, typically use single cavity molds for large—dia. and weight—-bullets. These are plain base bullets, the match rules exclude the use of gas checks. The first step of bullet quality evaluation is squareness of the base. You can see it after swinging the spruce plate over and before you open the mold halves. Mold fill-out can be immediately seen. If there is any “roundness” to the edge of the base, the bullet is rejected. 

Has there been extensive testing to explore the benefits of square vs. unsquare plain base bullets? Maybe but so far I’ve not seen reports of this kind.

Admiitedly the muzzle velocity of these rounds are quite a bit slower than the benchrest match loads being discussed here.

It would be interesting to see what the CBA match shooters in the PBB (Plain Base Bullet) Gun category/class think about the need for absolute square bases. Since they cannot use gas checks, they need to limit their muzzle velocity. Is an absolutely square base a must for accuracy?

Tom Gray got me hooked on the use of a bump die/press (back in 1997) and everything I’ve loaded over the years since for CBA match use, has been cycled through a bump die. I agree with the benefits of bumping that Tom outlines here.

Tom

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BudHyett posted this 13 December 2019

Tom Acheson's question concerning Plain Base Bullets has intrigued me for the last decade, Visual check out of the mold for base sharpness. weigh, then lubricate gently in a .320 die to assure there is no oversize band or slump in the body. Then select the bullets that simply look good. 

With the breech seat tool, in theory the tool pushes the bullet base square if the tool is a tight fit in the chamber. Any slight irregularities in the soft bullet body will be pushed straight into the leade and the bullet will start as true as possible.

I have a new tool shed coming for casting and reloading in the next week. Adding shelving and electricity, then moving in will take through Christmas. A structured test for both the .32-20 CPA and the .25-20 WCF barrels to prepare for next year's competition. The testing will include powder choice, powder charge, lubricant choice and Pb/Sn ratios. Once these are established, then work on the questions of base alignment and seating depth. 

Tex Johnston, the Boeing pilot who barrel rolled the new 707 at Sea Fair without anyone knowing he was going to do this said, "One test is worth a thousand expert opinions.”

Country boy from Western Illinois, living in the Magical Pacific Northwest

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Shopdog posted this 14 December 2019

It only matters,if it matters.

If the load and rig are in tune,and you have better than average,very clean bases, along with a good "driver" you may not see much gain in obsessing over it. But go outside "normal" for cast boundaries and it can turn a load around. I mill bases on a BP in fixturing that does 5 bullets at a time,in.... and with less effort than it takes to write this post. Again,depending on the rig/load/tune.... it can turn a 1 moa load into bugholes. My work is centered around killing varmints. 3 and 5 shot,DAILY.....rain or shine ragged hole groups at starting JB velocity is what I not only strive for but,honestly is what it takes in the field if you really want to "get after it". I'm not into reans of statistical data which is why I don't post more. Good luck with your project.

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Shopdog posted this 14 December 2019

"Reans" - reams. Can't even edit on here?

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Ken Campbell Iowa posted this 14 December 2019

shopdog .. good post ... optimism will get us there ... i cynically profess ...

editing .. if it is your post, your message will have on the top right side some faded blue words ... " quote   delete    edit " .... click on edit, you can edit your own message.  however, yes, computers hate us and are winning .....  the above works at least in windows 10 on my dell laptop ...  might be funny on a cell phone or mac ...

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Ross Smith posted this 14 December 2019

Back to the square bases on GC's,. My seating tool for the rcbs lubrisizor will gladly squish bullets and so will the push thru noe system unless they are hard enough. I agree that if looking for the best accuracy all of the above is important. But those crooked seated gc's will shoot ok for plinking and general shootemups.

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John Alexander posted this 14 December 2019

Shopdog,

Very interesting post. It wouldn't take reams of statistical data to prepare a short article for the Fouling Shot to share the results of your work so others could benefit.  Please consider the possibility.  Maybe even two articles one on your high velocity CB loads and one on the before and after of your base treatment.

I'm not sure what exact size a bughole is, but for 30 caliber or smaller they should be small enough to win the next CBA national championship. Please think about attending it is a great four days of shooting.

John

 

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Ross Smith posted this 15 December 2019

Thanks John, I finally read the article  you sent me. more people should read(re-read) it.

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mashburn posted this 20 December 2019

Congratulations to all of you guys involved in these good, interesting and educating posts. This is some of the most interesting and informative posts that I have read on the forum. Keep this thing going for a while/ Don't let it stop. PLEASE.

Mashburn

David a. Cogburn

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Ross Smith posted this 21 December 2019

Thanks Mash, your posts have helped me too.

I haven't forgotten about shooting some ugly wrinkled bullets too. i'm getting 32-40 tuned up and will shoot the ugly betties against some of the best I can do.

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John Alexander posted this 21 December 2019

Ross,

I will look forward to what you find with the wrinkled bullets.  A warning -- when you report someone will tell you you should strive for excellence and always cast perfect bullets as they do.  But I'll bet they have an ornery mold or two that on some days casts a small wrinkle in the bullet. They may throw all the wrinkled bullets back in the pot even if the bullets are for action pistol shooting because they have no idea whether they matter or not. So just ignore the flak. Some of us are curious about such things.

John

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Tom G posted this 22 December 2019

Guys,  

Whether or not you accept and shoot wrinkled or rounded base bullets is a personal thing. The important thing is to not cast them in the first place. 

A couple of weeks ago I made a long casting run to replenish my supply of 40 cal bullets that my son and I shoot in Action Pistol practice. Between the two of us we can shoot 200 a week when the weather is nice. Since I load for him too, I try to cast as many good bullets as fast as I can. One thing I try to avoid is casting bullets with rounded bases and or wrinkles. This last run was one of the best casting runs I've had in a long time. I cast 898 bullets in a little over an hour and rejected 38 for visual defects. One of the things I did to get good bullets right off the bat was to pre heat the molds. I started casting good bullets right off the bat because my alloy and molds were right up to casting temperature when I started.  

Long ago,I bought two electric hot plates for about 12 bucks apiece. I use them to pre heat my molds. If you start out with a mold that is already up to temperature your chances of casting wrinkles is very low. I found that with six cavity Lee aluminum mouds, if I set the temp. control to about 3/4 scale, it will bring my molds up to casting temp. in about 15 or 20 minutes. When I make my first cast, I have to wait for the sprues to solidify before striking off the sprue plate. If the molds are hot enough they will cast nicely filled out bullets that are a little frosty looking the first cast. While the molds are heating up, I also let the two pots that I use heat up too. After some playing around, I know what temp to set the pots to to get the frosty bullets I'm looking for. If they come out shiny, I up the casting temp or cast faster. 

Another reason you can get wrinkled bullets is a contaminated mold cavity. I had a friend who was in the commercial bullet making business. I used to do his tool and die work for him maintaining his automatic casting machines. Whenever he saw a cranky mold, he would pull it and clean it out in an acid bath. Then it would run fine again.I started doing that to my cranky molds and it eliminated the problem in most cases. Cavities can become contaminated from a lot of things but is you are careful to clean them before the start of a casting run, chances are they will run for a couple hundred casting cycles or more before having a problem. 

I clean my molds almost every time before I start casting. I use a kitchen cleaner powder that contains oxalic acid. There are two brands that are sold locally here in Southern Michigan. One is called Barkeepers Friend and the other is called Zud. They contain a mild acid that will help eat away the junk that builds up in your mold. I clean them in the kitchen sink using a tooth brush and very hot water. I also clean out and open up any vent lines that look suspicious. The hot water helps the aluminum molds to dry quickly. So, when I start, my molds look like new at the beginning of each casting session. They don't require any seasoning or breaking in after doing the acid clean. They cast good bullets right off the bat when they come off the hot plate. 

Using two 6 or 5 cavity moulds alternately at the same time, I can soon outrun a Lyman 20 lb. bottom pour pot. What I do is pre melt more alloy in a Lee 20 lb. dipper pot and ladle it into the Lyman pot if it gets below half full. Again, you have to play around with the pot temp. controls to get them both at the same temp. By throwing the sprues into the Lyman pot, I can make a pretty Long casting run with this method. This method and using a consistent casting rate will keep the bullets from wrinkling or making rounded bases. 

If I need to stop to make an adjustment to a mold or the pot, I put the molds back on the hot plate till I'm ready to go again and they resume casting good bullets right off the start.. 

Having your lead nice and clean makes a big difference. I usually flux it twice as a minimum. Marvelux is a great product. It not only fluxes well but it encapsulates the dross to keep it from getting into the air you breathe. If you look at the color of it before you skim it off, you can see how dirty it is. When you flux to the point that it stays fairly clean, you have some nice clean lead.  Also, I'm very careful when I lube the sprue plate pivot and alignment pins to not let lube gravitate into the mold cavities. If that happens, you have to stop and clean it or accept bad looking bullets. 

As an inveterate experimenter with cast bullets, I recently acquired a Ransom Rest. It cost me $400 plus two bags of shot to sweeten up the deal. I feel confident enough using it to work up loads for my pistols and revolvers. When I get through with it, I may sell it to another experimenter. After a casting run for my 9MM FN Browning Hi Power, I saved the bullets that had visual flaws. Once I find an accuracy load for the good bullets, I plan to shoot the rejects and compare them with visually good bullets for accracy. When I do, I'll report the findings to this group. 

In the meantime, I'll continue to re melt defective and wrinkled bullets as it only takes a few seconds to re melt them and they have a 99% chance of coming out just fine on the next casting. One nice thing about casting bullets is that you have zero scrap if you do this. 

Life's too short to shoot wrinkled bullets !!! 

 

Tom Gray

 

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John Alexander posted this 22 December 2019

Tom,

Absolutely great post! Please forward it to Glenn for consideration for the Fouling Shot.  I wrote such an article for TFS several years back but we get 40-50 new members every issue period (200-300 per year) and some of them are relatively new to casting so a good "How to Cast" article every few years is a good thing.  

Like you, I seldom have anything but visually perfect bullets from my tried and true molds.  I am confident enough of my bullets to shoot them in rifle competition without sorting them by weight and a lot of testing tells me that it isn't costing me points. 

The reason I sometimes write that small wrinkles or moderately rounded edges don't degrade cast bullets enough to be detectable on the target in most cast bullet shooting is because frustration with casting (and we have all experienced it -- think back when you started) is one of the reasons some beginning casters give up on the sport. Think of all the posts we have had here from frustrated casters seeking advice -- not all of them beginners. It happens. And it is discouraging.

Telling new casters to reject all visible defects instead of the truth that unless the defect is pretty big and unless they are working with a sub minute of angle rifle they will shoot just fine -- "go out and have fun shooting them while you are perfecting your casting technique. And by the way join the CBA and ask questions on the CBA forum for helpful advice to steepen your casting learning curve."

Glad to hear that you plan to evaluate wrinkled bullets in you new Ransom Rest. I wish more shooters were as curious.  Please plan on publishing the results in TFs as well as here.

John

P.S. When are you going to come back and shoot with us.  I miss swapping "war stories" with you.

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mashburn posted this 22 December 2019

Hello again,

To me, this post started out to prove what effects that imperfect bullets have on accuracy. It was just one of many variables that can affect accuracy .It wasn't aimed at casting perfect bullets. Example: It might prove that imperfect bullets aren't as bad as we think or maybe a pretty bullet can be flawed as to affect accuracy also. Lets not turn some good discussions into a seminar on casting pretty bullets, that Isn't what the contributors are trying to prove. No matter how pretty the bullet bases look, there can be problems.

Mashburn

David a. Cogburn

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Tom G posted this 22 December 2019

John,  Thanks for the kind words.  

You are right that we need to pay more attention to those souls who are just starting out. It would be great to have at least one basic article in each issue of the fouling shot. My last post might be entitled "How to be a faster caster" or something like that. We need to have at least one article per issue that addresses such things as Why do we have vent lines in molds. What happens when they don't work. How can I fix a mold that has a cavity with a bad vent line. etc..Guide pins, how to tighten them. How to not damage them.  Etc...  .  

As in our thread on bullet casting we're on now, Why do I get wrinkled bullets ?  How do I stop getting them?  How does my alloy effect mold fill out? How much tin should I use? What does the presence of tin in the alloy do? When do I need more tin?  How much is too much tin? What is Head pressure in a pot. How does it effect mold fill out? What causes fins on bullets?  Etc.. 

This could go on and on for a long time. 

I'm a big fan of the Lee Six cavity molds. With the advent of CNC machining, mold quality has recently made a great leap forward. When casting for action shooting, I use two, 6 cavity molds. That's 12 different cavities that are so close together in size and shape that the average shooter can just lump them all together and shoot them into wonderfully small groups. That didn't happen 55 years ago when I first tried casting bullets for an old .303 SMLE British rifle. This was with a single cavity steel mold over a Coleman stove and a hand ladle.  

As an example, I shoot a lot of 45 ACP in the Single Stack USPSA division. In that division, you have to meet a minimum power requirement called "Major Power Factor". To meet that requirement, I just chose a load that met the PF requirements with a little more for good measure. Using the Lee copy of the old H&G 68  200 gr. SWC bullet that Lee offers in their 6 cav. molds, Using that load,I knew they shot well but now exactly how well. As a result, I shot it in my 1911 at 50 yards using the Ransom Rest and got an 8 shot group of 2.65".  No one can say that there was anything wrong  with those bullets that can group like that with no load development. Granted, the gun has been tightened up and I installed a Kart barrel and bushing in it. But when you think about the fact that those bullets came from 12 different cavities, were only visually sorted and I was using mixed range pickup brass and were run on a Dillon 650 progressive machine, that's pretty good results from molds that you can buy from Titan, or FS (Factory Sales)  online for less than $40 apiece. I also have several NOE molds that are just as good if not better. No need to segregate bullet from them at all. And, these molds will last for thousands of bullets if you are careful and take care of them. We truly live in great times for casting bullets. The only problem is that the WW supply is drying up.  

I'll send that last post to Glenn and he can use it whenever he deems it appropriate. 

 

I'll sit back down now !!!!  Ha

Tom 

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Tom G posted this 22 December 2019

Sorry for the double post.  Things were running slow and I hit the send button again.  

TG

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joeb33050 posted this 22 December 2019

 

hoch filed base big.jpgTo see if damaged bases affected accuracy, I took a box of 18 Hoch bullets for the 32/35 Maynard, and made one file pass across the bases at about 45 degrees. This filed a flat defect on the bases, readily seen.

 

2/23/05 12/IMR 4227, Rem 2 1/2, breech seated, multiple cases, Model 1882 Maynard No. 16 in 32/35, Iron Sights, Hot and plenty of mirage. 100 yards, 5-shot group with perfect base bullets, then 5-shot group with damaged base bullets-alternating for 3 groups each.  
Group Sizes:
Perfect bases: 2.15", 2.20", 2.675" Avg. 2.342".
Damaged Bases: 1.2", 2.975", 2.025" Avg. 2.067"
On a good day, with one case and going carefully, this rifle has made many groups under an inch, probably averaging about 1 1/2 inches. The Irons are harder to see than ever.

 

Ohaus 45-405 bullets, 434.5 +/-.5 grains, Darr lubed, 21.5 grains SR4759, Dacron wad, WLP primers, breech seated, 100 yards, five shot groups, C. Sharps 45/70 Model 1875, 30X STS, Muzzle Clamp/Anti-Cant device.

 

 

 

45 405 filed base.jpg

 

 A set of bullets had the bases filed at a 45-degree angle for about half the thickness of the base band. Shot 3/2/05 to see the effect of damaged bases. Windy enough to blow empty plastic ammo boxes off the bench, 70 degrees, bright sun, plenty of mirage. Alternating perfect and damaged bases.

 

 

 

 

 

Group sizes:

 

Perfect bases: 2.1", 4.3", 2.05", 3" Avg. = 2.863"

 

Damaged bases: 3.35", 2.675", 3.95", 2.9" Avg. 3.219"

 

I thought there might be lead in the barrel, couldn't find any. I read through the notebook on this rifle last night. Many 10 shot 200-yard groups under 4", many 100 yard 5-shot groups under 2", some under 1", one measured .693"-all with this load. I've used the Wolf No-Grease-Groove bullet almost exclusively in this rifle since 1993. I don't know why I'm shooting such big groups in this damaged bullet testing-but here it is.

 

Maybe these damaged bases caused the larger groups.

 

3/23/05, nice and windy, with gusts, varying from bright sun to rain showers. About 84 degrees with excellent high humidity. Martini 30/30 bench rifle, Lyman 20X STS, Wolf No-Grease-Groove 213 grain bullets with two coats of Lee Liquid Alox, 12.5/AA#9, Remington 2 1/2 primers. One hundred yards, five-shot groups, one sighter, shoot two groups, clean.

 

Good bases 1.1", 1.6", 1.825" Average 1.508"

 

Filed bases, 45 degree at the edge 1.325", 1.65", 1.075" Average 1.35"

 

As an aside, I also tested 311299's from a "Beagled" mold, these averaged 1.069" for four groups with the same load.

 

The Wolf NGG bullet has always shot adequately if not as well as other bullets in this rifle, but sometimes leads about a foot up the barrel-hence the cleaning.

 

This is the third test.

 

It starts to look like we can say that damage to the edges of bullet bases doesn't radically affect accuracy.

 

3/22/06 308403, Darr Lubed, Rem 2 1/2 primers, one case, 7/Unique, 30WCF M54 Winchester, 30X STS, Sandbag bench rest (Hoppes). 85 degrees, very windy, clouds then clear, very hot in the sun. 100-yard five shot groups. 26 bullets had the bases filed at a 45-degree angle to make a defect about half way up the base band. Fired about 6 sighters and stopped. Next relay (15-minute relays) fired 1 fouler, 5 filed base, 5 good bases. Next relay fired 1 fouler, 5 good bases, 5 filed bases. And so on, alternating the first group shot between filed bases and good bases.

 

Filed Bases 2 .375", .825", 2.4", 2.5", 2.4" Average 2.1"

 

Good bases 3.3", 2.55", 2.3", 2.2", 2.3"    Average 2.53"

 

There are a lot of bullets tipping. Maybe need more powder or Dacron; I've used 7.5 grains/Unique and Dacron in the past.

 

This bullet generally shoots into about 1.5" averages at 100 yards. Maybe the wind, which will stop in July, when it gets REAL hot.

 

Again, I don't think that filed/damaged bases shoot better than good bases, the .825" group is a fluke.

 

3/29/06 308403, Darr with some beeswax lubed, WLP primers, 7.2/Unique weighed/dribbled, Dacron wad tamped down on powder, 30WCF M54 Winchester, 30X STS, Muzzle clamp/anti-cant device, flat bench rest. 79 degrees, slightly windy, clouds then clear, 100-yard five shot groups. 26 bullets had the bases filed at a 45-degree angle to make a defect about half way up the base band. Fired 6 sighters and stopped. Next relay (15-minute relays) fired 1 fouler, 5 filed base, 5 good base. Next relay fired 1 fouler, 5 good base, 5 filed base. And so on, alternating the first group shot between filed bases and good bases.

 

Filed Bases 2.55", 2.2", 1.5", 2.525", 2.85" Average 2.325"

 

Good bases 1.125", 1.325", 2.3", 1.275", 1.8" Average 1.565"

 

Most of the bullets are still tipping.

 

Finally, the damaged base bullets shoot larger groups than the good bases.

 

4/5/06   308403, Darr with some beeswax lubed, WLP primers, 8.0/Unique weighed/dribbled, Dacron wad tamped down on powder, 30WCF M54 Winchester, 30X STS, Muzzle clamp/anti-cant device, flat bench rest. 84 degrees, quite windy, clear, 100-yard five shot groups. 27 bullets had the bases filed at a 45-degree angle to make a defect about half way up the base band. Fired about 6 sighters and stopped. Next relay (15-minute relays) fired 1 fouler, 5 filed base, 5 good base, cleaned barrel with 2 patches and MM oil. Next relay fired 1 fouler, 5 good base, 5 filed base, cleaned barrel. And so on, alternating the first group shot between filed bases and good bases.

 

Filed Bases 2.2", 3.7", 1.95", 1.525", 1.275" Average 2.17"

 

Good bases 1.7", 2.0", 2.6", 1.825", 1.675" Average 1.96"

 

Maybe half of the bullets are still tipping.

 

Those shot 4/5/06 were from a lot that weighed 170.6 to 170.9 grains. I just filed the base of one out of that lot. It started at 170.8 grains. After filing it weighed 170.5 grains. The filing lost .3 grains.

 

4/12/06 308403 lubed with Darr + some beeswax. 11/AA#9, WLP primer, CF Ventures soft gas check, Martini 30/30 bench gun, 30X STS, muzzle clamp/anti-cant device, flat bench rest. Five shot 100-yard groups, 1 sighter and 2 groups per 15-minute relay. Bases on some bullets filed at ~45-degree angle ~ half way up the base band. It was 82 degrees and windy. How windy was it? My Gatorade plastic bottle cap blew off the bench, my gun case blew open (it was slightly open) and a set of sky screens with holder and tripod blew over twice. I have little experience with this bullet in this gun.

 

Six of 25 shots with both good and filed bases were tipping.

 

Good bases 2.725", 1.175", .625", 1.45", 1.7" Avg 1.535"

 

Filed bases 3.125, 2.675, 1.45", 3.45", 1.025” Avg. 2.345"

 

Summary to date

 

                        FILED            GOOD

 

                        BASES           BASES          

 

3/22/06            2.1"                  2.53"   

 

3/29/06            2.325"              1.565"

 

4/5/06              2.17"                1.96"

 

4/12/06            2.345"              1.535"

 

 

 

Damaged Bullets, Distinction and Difference

 

            After looking at forty groups fired, half with filed-base bullets and the other half with "good" = unfiled-base bullets, I've been assailed by a conclusion, to wit: Not all bullets with damaged = filed bases fly wildly to the target. The probability that any given bullet will land out of the group is greater shooting bullets with damaged bases.

 

            I first thought that this was a distinction without a difference-it's starting to look like bullets with damaged bases make bigger groups than bullets with good bases. But I think that I see a difference.

 

            All our bullets would go through the same hole, we think, if not for the differences that creep in amongst our loads. Differences in brass or bullet or powder or primer or bore condition or weather or any of the dozens of variables. These differences, some or most of us suspect, yield shots outside the group. And my assumption, shared, I think with others, is that if we assembled and shot a set of loads, all with a given difference, the groups would be larger than if that difference were not present. And we suspect that that is true because the differences make the bullets fly out of the group.

 

            Now all bullets with damaged bases do not fly out of the group, some of them fly into very nice groups and others fly into nice four-shot groups with a flyer, or three shot groups with two flyers, or....

 

            Since the filed-base groups look to be larger, probably bullets with damaged bases make larger groups on average than do bullets with good bases. Think of two normal-looking overlapping distributions.

 

            This is where I get stuck. A bullet with a forty-five-degree filed surface for about half of the height of the base band should fly to a different place than an unfiled bullet. And with no specific orientation of the bullet with the bore, these filed-base bullets should make a "big" group.  There are any number of folks who can explain why these bullets should make these big groups. They do make bigger groups, on average, I think. But, why are some filed-base groups smaller than good base groups? Why doesn't every filed-base bullet fly out of the group? Why is this a probabilistic process?  If damaged bullet bases cause the bullet to fly out of the group, why doesn't every damaged base bullet fly out of the group?

 

            A cartridge without a primer doesn't go off, and it doesn't go off every single time. There's no business about it doesn't go off 96% of the time, it doesn't go off.

 

            If damaged bases cause bullets to fly erratically, then every bullet should fly erratically. Every bullet.

 

            Perfect loads make one hole.

 

            Real-world loads make groups with the greatest density of the shots in the center, and reduced numbers of shots as the distance from the center increases. Dense in the middle, density decreasing as the distance from the center increases.

 

            Loads with an intentional defect oriented randomly should make groups that look like a doughnut, with maximum density at some distance from the center, diminishing both toward and away from the center. I don't think that they do.

 

            So, I'll make a bunch of filed-base bullets and fire them at one aiming point. Maybe thirty or so. And I'll fire a set of good-base bullets at another aiming point.

 

            I'm thinking that if I don't get a doughnuty looking group from the filed base bullets that maybe we need to re-think some of those explanations.

 

4/26/2006   M54 Winchester 30WCF, 30X STS, 12/AA#9, WLP primers, CF Ventures Soft Gas Check, 308403 lubed Darr + beeswax, muzzle clamp/anti-cant device and flat bench rest. 65 bullets had 45 degree filed bases to about half the height of the base band. A set of 18 cases had file marks put on the base and rim for orienting. A fouler was shot before each set of shots, at the center dot. Bullets were put in the cases with the filed bullet marks at 12, 3, 6 and 9 o'clock, four shots, and the cartridge was put in the chamber with the case base/rim mark at 12 o'clock. Then as precisely as I could put the bullet in the case and then the cartridge in the gun, bullets/filed bases were oriented each shot.

 

Four with filed bases, four perfect bullets, then four with filed bases and four perfect bullets; with a sighter comes to 17 shots per fifteen-minute relay. 64 shots each with filed and perfect bases were made. All shot at 100 yards.

 

The weather varied from sunny to rain, still to very windy. In the still sunny conditions, there was a lot of mirage, and biting horseflies about the size of robins. Lots of "damn"s and slapping body parts.

 

The damaged base group is 3 9/16" high by 4 11/16" wide, with no discernable pattern. The perfect base group is 2 7/8" wide by 2 1/2" high with the center shot out and outliers ~evenly distributed.128shotsC.jpg

 

 

 

It is clear from the target that bullets with damaged bases do not shoot wildly, that many of the bullets cluster into a small group, and that the group/distribution is not doughnut shaped. This suggests that the mechanism decreasing accuracy is not one that operates every shot, but is probabilistic in nature.

 

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John Alexander posted this 22 December 2019

It seems remarkable that even with the gross defects Joe filed on his bullet bases they didn't shoot that much worse than the good bases. Not what we have been told would happen.

John

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Ross Smith posted this 23 December 2019

I'm amazed at all the excellent replies and comments. 

Just a note to Tom G.'s comment. I cleaned a mold that had been in storage and oily for about a year. I used comet cleanser and a tooth brush. It took 3 sudsings to get the steel to where it would "wet out" with water and not have the water bead up. That means the oil is gone.

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Tom G posted this 23 December 2019

Ross, 

You might try heating the mold up to casting temperature on a hot plate or with a propane torch.  You might be surprised at the amount of oil that will still come out.   

Zud or Barkeepers Friend is worth trying or any other kind of cleanser that has oxalic acid. It doesn't really seem to abrade the crud off the mold but eats it off.   

 

Tom

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John Alexander posted this 23 December 2019

In an attempt to get this thread back to the original bullet base topic instead of how to cast.  I submit the following thought.

It seems to me that if we want to learn something USEFUL instead of only interesting in an abstract way the question should be --will slightly tipped gas checks or small to medium casting defects on the base cause inaccuracy and if so about how much inaccuracy. When should we correct, reject, or just use and enjoy?

To me, seeing what gross defects (bullets that won't stand on their bases or 45 degree file cut half way through the base band) do to accuracy is interesting but we can't put it to much use for two reasons 1. such extreme defects are seldom unintentional. 2. We aren't crazy enough to use such gross defects for any serious shooting.

On the other hand small defects (hard to detect skewed gas checks or minor rounding or small wrinkles at the base) happen more frequently and  it is harder to be sure they are eliminated. It would be useful to know how much damage, IF ANY, these do to accuracy -- at the 1, 2, 3, and  4 moa level

As things stand, all we have is the absolute statement "bases need to be prefect".  I don't think we have the experimental data to back up this statement. 

John 

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Ken Campbell Iowa posted this 23 December 2019

 ... i am still stuck on " beagling " ...  apparently our chambers are a kind of swaging die .. and heal " beagled " bullets ...

maybe they heal bent bases also ... ( actually as reported " yes " above ) ...

the longer the bullet, the better they heal the bases ... ? ...

************

here is a thought that plagues /amuses me: ...  assuming that in a perfect system the bullet strikes on the crosshairs ... an imperfect bullet with only one imperfection strikes in a probability circle around the crosshairs ....  but a bullet with two imperfections strikes in a probability circle of the 2nd imperfection around the circle of the first imperfection ... and so forth ... like naughty children having naughty grandchildren ....

... and so a graphic of these fuzzy circles would show us that some per centage of these arcs lie within the parent arc ... and so we see that not all defective bullets increase the radius of the immediate parent circle ... 

some of the bullets fly * into * the group ...  as the parent ( bad defects ) gets very large, half of the bullets of the children fly into the parent circle ... if the parent is really good, fewer of the child's bullet fly into the parent circle.

*************

and so we have kind of a " flashbulb testing " problem .. we don't know how a defective child  affects the parent until we know how imperfect the parent was ... and by that time we have shot the parent ...

...but if we have a perfect parent ( benchrest mj ? ) we can get a better understanding of the naughty child ...

******

anybody for beveling some mj bullet bases ?   ( 60 cents each at last pricing ) ...if you have a benchrest 6mm, i can send along a hunnert or so if you let us know the results.   gotta see that big circle around the crosshairs they are supposed to make.  pm me if .. or if someone wants some match 6mm  mj at good price.  ( euber or yingst ... all mollied )

ken

 

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John Alexander posted this 23 December 2019

Ken,

Maybe swaging at time of firing heals beagled bullets.  Maybe beagled bullets don't need to be healed.  Everybody likes "perfectly round bullets".  I have some molds that cast as perfectly round bullets as I can measure but they don't shoot as well as some bullets from less than round molds. Why shouldn't an elliptical bullet (or other less than round shape) shoot OK? Do we really know? 

Your dissertation on naughty children and naughty grandchildren is right on. I believe Joe has the statistical tricks to predict the net accuracy loss of several naughty children (the cumulative resulting error from several contributing errors) in his book. That's why small errors don't count for as much as we expect and why farting around with prepping cases, cleaning primer pockets, and weigh sorting bullets aren't reasonable use of most cast bullet shooters time -- the "parent's" defects are too large. 

This is especially true for shooters shooting 2" or larger five shot group averages (most rifle cast bullet shooters and all revolver and auto pistol cast bullet shooters.)

John

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John Alexander posted this 23 December 2019

Ken sez:

" gotta see that big circle around the crosshairs they are supposed to make."

You don't have to have a mj benchrest rifle to shoot a big circle around the crosshairs.  Such circles have been posted on this forum at least twice.  One (along with a lot of other interesting stuff) by the fellow using the handle of "Husker" using a 22rf bench rifle and one by me using an old chopped down M-37.

You don't have to have a perfect parent but only a parent (rifle) much better than the very naughty child (controlled defect).  You also have to orient the defect at different positions around the clock in the chamber to get a circle.

I believe I can find a picture of my "circle"  ( which was just the naughty child shots ar 3, 6, 9, and 12) if anybody wants to see it.

John

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Squid Boy posted this 23 December 2019

Excuse me for getting a little off topic but I read Tom's post and the part about cleaning your mold with Zud or Bar Keepers Friend  really hit me. I have an old Lee 45-405HB mold that defied everything I could do to make it cast a bullet without some sort of defect on one side. There was some sort of black stuff in that cavity that would not give up. However, five minutes with Bar Keepers Friend was all it took and the mold looks like new. I just finished casting 20 as a test and the weirdness is gone. Just wanted to comment. Thanks Tom and Merry Christmas to all. Squid

"Squid Pro Quo"

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mashburn posted this 23 December 2019

Hello again,

I've been thinking and that is sometimes dangerous for me and others. Is it possible that plain base bullets, that I presume have semi-molten bases when they leave the muzzle, no longer have sloped or irregular bases and this could be why they don't seem to be affected by the bad base. In other words the bad base has been turned back to flat by the time it exits. As Ken said, the barrel is a swage and the hot gases act as a swage to the base of the bullet.  On the other hand gas checked bullets do not have the semi-molten base and therefore leave the muzzle with the gas checked base still crooked.

Also gas checked bullets are normally fired at higher velocities than plain base and the higher velocity would cause the defective based bullets to fly more erratic. It's time for me to quit writing because I am doing more dangerous thinking and someone including me could  be injured and my insurance doesn't cover that.

Mashburn 

David a. Cogburn

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RicinYakima posted this 23 December 2019

David,

It has been represented to me that the "plastic" base of the bullet is not from heat, but pressure. The pressure exceeds the strength of the alloy, not to be confused with hardness. Yes, gas pressure is perpendicular to the base. With the same alloy and same pressure, a gas checked bullet forms the plastic state the same, but has a physical piston to drive it. The shank of above the gas check is just as soft with or without the gas check. That is why I don't worry about little lumps or divots under the gas check, it is all the consistence of bubble gum at the beginning of the bore.

FWIW, Ric

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mashburn posted this 24 December 2019

Hello RicinYakima,

First of all gas takes the shape and volume of its container. If a gas checked bullet becomes elastic as much as a plain base bullet does, there is another problem with that theory that you gave. In order to square the gas check up on a bullet, the pressure would have to be higher on the high side of the gas check. In reality, I think the gas pressure would be deflected toward the lower side of the bullet base and actually increase the angled base and GC. This thread is getting a way to complicated for my brain, but there sure has been a lot of good information to think about and experiment with. When the posts about flyers were put on this thread I wanted to carry that out but I didn't want to take away from the original subject of the discussion. If I don't forget it I'm going to start a post dealing with flyers.

Thanks for your response, it gave me more to think about. It's getting on toward 2 AM and  about time for me to stop. I'm a night owl and I can come up with lots of ideas in the wee hours.

Mashburn

David a. Cogburn

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45 2.1 posted this 24 December 2019

It has been represented to me that the "plastic" base of the bullet is not from heat, but pressure. Both actually... The pressure exceeds the strength of the alloy, not to be confused with hardness. Strength? Which particular strength (compressive, shear, torsional and has nothing to do with tension). Alloy? air cooled or heat treated... there is a BIG difference in how each condition acts with the same alloy... Yes, gas pressure is perpendicular to the base. That's in a static condition or fully engraved in the barrel... otherwise think of a pool ball bouncing on the pool tables bumpers... that's a pure dynamic condition... With the same alloy and same pressure, a gas checked bullet forms the plastic state the same, That's too big a statement and needs some qualifying. Alloy and it's treatment (air or heat treated) vary widely with static hardness let alone when it reaches it's yield point in a moving dynamic condition. Everyone is delving into areas where you need to talk to a materials engineer!..........................

 

This is a lot more complicated than most all here believe. I spent my professional career dealing with materials and how they fail under load, but I really don't expect you to believe what I've just written............................................

 

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RicinYakima posted this 24 December 2019

" but I really don't expect you to believe what I've just written............................................"

Of course I believe what you wrote above.

"This is a lot more complicated than most all here believe. "

Especially that statement.

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John Alexander posted this 24 December 2019

Trying to envision what goes on inside a case when things pop is pretty hard although fun to think about.  That doesn't mean that we can't make some progress understanding, or partially understanding it.

For instance Max and Ric wonder if the gas pressure doesn't sometime seat a crooked gas check. It can, and 45.2 has observe it which isn't surprising.

Gas does take the shape of its container but only if it has to.  it is happier changing the shape of its container and if it has enough pressure -- it will as in forming sharp shouldered cases from factory brass, or blowing up a perfectly good rifle.  It's true that it isn't static pressure and it is rushing around in some sort of a turbulent firestorm but it is still probably pushing pretty much perpendicular to the surface at any point because there is little way for a gas to get a grip on a smooth surface and push other than perpendicular.  Gas will deform its container most where it is weakest (the unsupported shoulder area in an AI chamber) and if the high side of a crooked gas check is the weakest it will be pushed until seated more firmly. If we could only depend on it working every time which if may, or may not.

John

 

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Squid Boy posted this 24 December 2019

I agree with John about the gas altering the container to a point. I think that the case being the weakest will be forced to conform to the shape of the much more resistant chamber. However, the bullet base is another part of the container and while plastic under high enough pressures I tend to agree with Dr. Mann's finding that oblique bases do not repair from the action of gas pressure and they remain defective. I believe that is because the pressure is applied in all directions equally even with a pressure wave front hitting the base. I think the unsupported part of a crooked gas check is subject to move until it contacts the bullet base. I am also speculating about these things from some limited observations but it is certainly an interesting topic. Squid Boy

"Squid Pro Quo"

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Tom G posted this 24 December 2019

Squid Boy,  Glad that worked for you.  If a mold still won't work right after the Zud treatment, try heating it up to drive any remaining oil out of the pores.  Do this till you get no more oil and then zud again. 

Angled bases.

My test with the bullets with the gas checks on crooked showed fliers that probably doubled the group size.  When I shot bullets that had square bases, they grouped in the normal size with no fliers.  Kind of tells me that crooked gas checks don't square up and that they do cause fliers. And they definately cause fliers.   

Dr. Mann's Experiments

I dug out my hardcopy of Dr. Franklin Manns book called The Bullets flight   The ballistics of small arms.  On June 11, 1903 they did test # 131.  It was shot through a new Pope barrel that they noted had guilt edge accuracy in a V rest. . Shooting took place in the evening under favorable shooting conditions. (no wind).  In this test, they shot bullets with the swaged bases. 

They swaged the bases at two different oblique angles. One group had a base angle of of what they describes as .012" and the other group was .006".oblique.   They shot a control  group with good bullets that was .61".  They also clocked the bullets in the barrel so that they would emit from the muzzle with the oblique side at 12, 3, 6 and 9 O"clock at the muzzle. 

They noted that only one shot in 8 hit within the circle around the group made by the control group. They showed a photo ot the group that resulted from the oblque angle bases bullets shot into the same aiming point as the control group.  of the eight shots with the 12 and 6 thou. oblique bases , it shot a hollow group with two hits in each of the 4 quadrants. Each of them shot into a predictable and repeatable spot on the target according to the way the bullet oblique base emitted from the barrel. 

The only unexplained anomoly was the the ..006 bullets shot into a slightly smaller group than the ones with the larger .012" bases. The oblique bullets shot into a group a little more than twice the size of regular bullets. 

My impressions. 

.006" obliqueness on say a 32 caliber bullet is not very big.  Yet it had a big effect on where the bullets struck the target. 

Please note that these bullets had bases that were swaged slightly oblique. Not filed oblique. Thus, as in Joe's test, if I understand it correctly, they were not unbalanced from taking material from one side more than the other. Therefore , only one variable was tested at this time. Notably, only oblique bases on bullets that weighed the same and were left in balance. 

Also, there was no evidence that they were repaired in any way by the pressure exerted equally on all of the bullet base upon combustion. 

Thought I'd pass that on for you guys who don't have access to this book.  

 

Tom Gray. 

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Ross Smith posted this 25 December 2019

Me again. My really crooked GC's happen when I use my lube sizer and are pretty well  swaged into that offset. If I pull a gc to check the base, it too has been skewed and gouged. I doubt that firing the cartridge will cure all that. I still stand by my statement that crooked gc's are ok for plinking. I never would suggest them or other flaws for comp or just striving for your own best accuracy. I am also really impressed with the knowledge and thought coming from this post. Can't say that enough.

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max503 posted this 26 December 2019

So...……...is there an efficient manner of trueing up bullets with less than stellar bases?

I've got a large handful of Lee 55 grain 22 bullets, and many of them have protruding scars from where the sprue was cut.  

It would be nice to use them instead of melting them.

What if I laid them in a vee block and trimmed the scar with a box cutter knife?

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Ross Smith posted this 26 December 2019

Al Nelson taught me a little trick of chucking the bullets in a drill press and spinning them on a plate. In my usual "that's too slow" mode I switched to 220 grit sand paper. When a 30 cal bullet leaves a 30 cal "smear", you're done.  Still too much work for plinkers and beer can shooting.

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John Alexander posted this 26 December 2019

Max,

Why not try it?  I have already given my opinion about it fixing your peachbasket groups but I have been wrong a lot.

I have a suggestion for you to consider after you have tried a few reloaded as you have been.  Set aside 100 of those bullets.  Trim off the bumps in a vee block as you suggested. Save this 100 bullets until you get your groups averaging 1.5" or smaller for five shot groups and then run a comparison test as I described in TFS #257.

If you would do that and publish the results in the forum and in TFS.  It would make interesting reading and add to our knowledge of what works and what doesn't.

John

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max503 posted this 26 December 2019

OK.  You guys have given me several things to try.  What more could I ask?  

John - thank you for the FS.  I will read that article.  (I don't know what happened to my download.)

I was halfway kidding about trimming those bullets, but I will give both methods a try.  Both the knife and the drill press.  I don't need many.  I'm shooting a bolt action not an AR.

I will be glad to do a write-up if I can get something to work.  That's a deal.

Wish me luck.

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Hamish posted this 09 January 2020

Perhaps I have missed it, if so, I apologise.

I do not remember ever seeing discussion regarding the inherent accuracy differential between nose pour versus base pour.

 As 45 2.1 has regularly repeated for many years that the errant mal seated check can be counted on to be fully seated before muzzle exit, I cannot help but wonder about this question as it seems to me that with base pour, relatively perfect bases can only occur somewhat regularly.  

Whereas, with the nose pour, if good fill out is repeatable, then the base is necessarily square and "perfect" every time.

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Ross Smith posted this 09 January 2020

H.    When I see one of my mangled GC's crooked bases bullets that can't stand up on a flat table, it gets recycled. I don't know how that base can be squared up by firing it down a barrel without something else being screwed up. It's the little "mis alignments" that are under question and I agree with your observations, my base pour molds don't deliver nearly as good a base as my nose pour molds. But I don't think we need to be too picky about bullets that are going to be shot at a gong. 

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John Alexander posted this 09 January 2020

Hamish wrote:

"I do not remember ever seeing discussion regarding the inherent accuracy differential between nose pour versus base pour.

I cannot help but wonder about this question as it seems to me that with base pour, relatively perfect bases can only occur somewhat regularly.  

Whereas, with the nose pour, if good fill out is repeatable, then the base is necessarily square and "perfect" every time."

=================

You have recited the seemingly logical reason why nose pour molds should produce superior accuracy.  This belief has been around for well over a hundred years. However,  like a lot of superficially logical theories that are also "just common sense", it apparently isn't true at least at the level of accuracy we have been able to achieve with cast bullets [aggregates (averages) of 5-shot groups of about 0.5 moa.]

This theory has been disproved by the actual results in supervised shoulder to shoulder CBA competitions over forty years.  Nose pour molds have gone from being considered necessary by most serious shooters to comprising less than ten percent usage at CBA national tournaments. If bases good enough to win matches were hard to achieve with base pour molds they wouldn't have become the overwhelming choice.

There seems to be a lot of evidence that both the need for absolutely perfect bases and our belief in what we call common sense are both vastly overrated and actual competition and/or well designed scientific tests are both superior for finding out what is true and what is just what we have been told.

John

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Ross Smith posted this 09 January 2020

I never thought this would generate 3 full pages of comments. In the end,let's go shoot.

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John Carlson posted this 10 January 2020

Temperatures in single digitsdepressed, winds occasionally over 40 mphconfused, let's just talk about shooting for a bit longer134

Holding public office should be viewed as an obligation to serve, not an opportunity to rule.

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Hamish posted this 10 January 2020

Thank you John.  As I never developed much interest in CBA style shooting and history until well after my IHMSA days where cast was merely a cheaper way to practice and handle the banks of chickens, I'm mildly ignorant of the minutia of these things.

The habit of eliminating the basics as contributing factors is sometimes a help, sometimes it is not.

Though my endeavors will always be the rather pedestrian pursuit of acceptable hunting/plinking accuracy, I do appreciate the forum and its contributions.

 

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JBinMN posted this 14 January 2020

This is an exceptional read, IMO, and I thank all of you for your contributions!

 

JB

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madsenshooter posted this 14 January 2020

My first experience with cast bullets was all about basing!  I started my efforts with a Lee single cavity tumble lube 160gr bullet out of a 92/96 Krag that I'd scoped with a Krag Haus mount.  Using bluedot for powder I wasn't doing too bad from the very first experiment maybe 4" groups at 100yds, with unexplained fliers.  I was using a push through sizing die in the beginning, and found some of my fliers in the fact that I wasn't tapping the checks all the way down onto the shank before sizing.  There was also an issue with outtie sprues that wouldn't let the check seat squarely.   Then I won an auction on ebay for a cherry for the MX3-30-AR from the Don Eagan estate, and had Bernie Rowles make me a mold with it.  I couldn't believe my eyes as I watched the first group form from about 70yds!  12 or 13rds, most them touching like I later saw the benchrest shooters at Washtenaw shoot, out of a 125yr old rifle with a $30 scope!  One flyer about an inch out was called as I felt the rifle slip a bit off the rest, which was the bannister of my back porch, about the same time the striker was falling.  Since then I've gathered Eagan molds, both original and some made with the cherries I have, and other Eagan things, like the coin gascheck seaters for several calibers, a tapered 30 caliber size die and a little die that tapers a 30 caliber gascheck shank.  I use that one to restore the taper on a B&M 311169 that someone decided to make larger at the rear.  I think basing is very important!  Just got me a Hoch 314225, any of you have any experience with that bullet?  I'm hoping my Krag will like it!

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