Bullet Weight Varience

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  • Last Post 27 March 2020
4and1 posted this 25 March 2020

For those that shoot the cast bullet benchrest matches, I would assume you weigh each bullet after casting to cull those out of.........? So my question is, how much plus-minus do you keep?

I don't go too crazy, I just use my chargemaster to weigh each bullet. I make a pile of each per tenth of a grain, and see how they play out. To me, I pick the "middle" weight, then give 2 tenths plus and minus, for my 200 yard bullets. Depending on how they all weigh out, I give a little more variance to shoot 100 yards.

The bullets that are out of the "good", I keep and powder coat those a different color and use for fowlers after cleaning the barrel.

As a bit of an aside, on another thread, it was asked about GC before or after PC. I seat before, I use a seater I made that is drilled and reamed to bullet size, with a small cut for the GC in the bottom. I seat the GC using an arbor press, then shake and bake. Never had a GC come off.

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TRKakaCatWhisperer posted this 26 March 2020

THE best practice I've done was to weigh EACH bullet just after casting.

It taught me to tighten up on temperature and times.

After I got to being able to cast most bullets +/-1gr for 200 gr bullets I stopped weighing.

SOME folks use a tighter tolerance.  Some folks don't weigh at all.

 

 

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45 2.1 posted this 26 March 2020

^^^^^^^^^ Great post. That tightening up temperature and times is a way to produce excellent bullets. The key to match grade bullets is a minimal temperature heat cycle swing between casts with a like cycle time between casts along with using a scale to determine how to get bullets with little or no variation in weight. It is much easier to shoot good to excellent groups with bullets that all weigh the same as cast than by sorting by weight because weight sorting does not pick up differences in diameter.

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John Alexander posted this 26 March 2020

4and1 asked: "So my question is, how much plus-minus do you keep?"

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A poll of the shooters at the last CBA National Tournament indicated that 0.1 grain + or - was the most usual range with 0.2 grain + or - was the second most popular. The average weight of the bullets was a little over 200 grains.

However, 28 percent didn't weigh their bullets at all, and that included some of the winners. This shouldn't surprise readers of the Fouling Shot where articles have been published showing that sorting bullets by weight doesn't improve group size.

If you really think sorting bullets by weight improves accuracy you could run a simple test to find out instead of just blindly doing it because it seems like a good idea.  Sort half the bullets from one casting by weight and shoot them in alternating groups with the other half of the bullets that haven't been sorted.  Shoot at least 5 five shot or 3 ten shot groups of each type. If you find that sorting improved accuracy please publish your finding in the Fouling Shot because you will be the first to find improvement.

I suppose it is possible to cast bullets bad enough that sorting by weight improves them but for any good looking bullet cast with attention to achieving minimum temperature variation as urged by the two posts above, sorting by weight is a waste of time. 

Sorting by weight does have the advantage of keeping shooters at home and reduces the time for running around in public and maybe catching or spreading any infectious disease present. 

John

 

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45 2.1 posted this 26 March 2020

Of course, there is the premise that the shooter isn't shooting adequately enough to tell the difference. A lot of these things do show up when shooting longer ranges and at higher velocities. Exactly at what point is good enough to actually tell what does make a difference and does it matter. Comments?

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4and1 posted this 26 March 2020

This is the kind of feedback I was hoping to get, thanks all. I try to maintain a rhythm. I can say, I had less culls using a single cavity as apposed to a double cavity. 

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John Alexander posted this 26 March 2020

45 2.1, If I understand you correctly, you are absolutely right.  For instance my tests of sorted vs. unsorted bullets were done with a rifle, load, shooter combination capable of five shots groups averaging slightly under one minute of angle. The average group sizes of strings of five shot groups alternating between sorted and unsorted bullets were always very close to equal.  Sometimes the sorted bullet average would be a bit better. Sometimes the unsorted bullet average would be a bit better. Never a significant difference either way.

If sorting made no difference at average group sizes of 1 moa is sure as heck is not going to help rifle, load, shooter combinations averaging 1.5 moa or bigger which probably includes 95% of the cast bullet shooting being done.  For that 95% of CB shooters it looks like sorting doesn't help.

I certainly wish someone with a rifle-load-shooter combination capable of averaging near .5 moa would test weigh sorted vs. unsorted bullets so we would know if sorting helped shooters shooting at that rarified level. Unfortunately I know of no such test that might show whether sorting is helpful -- or not.  

My tests were also limited to 200 yards  and less and I agree that sorting may turn out to be helpful at longer ranges but I know of no experimental work that has shown this -- maybe, maybe not. The same for longer ranges. It  could be that sorting helps high speed loads,  but I have never seen test reports proving it.

John

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4and1 posted this 26 March 2020

I have posted before I have shot BR for a long time, and I make my own jacketed bullets. Whether J's or cast, variables have to be reduced as low as possible. Keeping bullet weight the same can only help, does it show on paper, don't know. When I was testing powders, I was throwing charges, and shooting over a chrony. A slow velocity in a string almost always showed a low hit at 200yds. Weighing powder helps this.

200 yard shooting shows more. A 100-200 yard match is won at 200.

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John Alexander posted this 26 March 2020

Most folks who haven't dinked around with statistics and probabilities would say that any reductions in any variable MUST help. But if you can't make something show of paper or measure it is it really there. Or if it's somehow "there" but it never shows does it make any difference?  Only in religion.    

CB shooters often sort to 0.1 grain, so bullets that vary 0.2 grain are culls.  For a 200 grain bullet that 0.2 grain is 0.1% or one part in 1,000.  They are shot in rifles where the chamber pressure to push the bullet often varies 10% or more from one shot to the next. This is 100 times the variation in the bullet weight. Maybe this is why you can't see any improvement on paper for sorting by weight.  To use another example it's like a fart in a tornado.  If the fart was pointed, in the right direction, it theoretically helped blow down the power line but fine tuning the fart doesn't really make any difference.

I recently weighed a box of Berger 60 grain 6mm match bullets. They varied .5%, -- five or ten times as much as some of my friends sort their CB bullets.  Yet my PPC, and those bullets, will shoot groups half the size of the best CB shooters no matter how fine the CBs are sorted.  If tiny bullet weight variation was needed those Bergers wouldn't shoot.

John

 

John

 

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RicinYakima posted this 26 March 2020

Dip my oar in the water since I here in the house on lock down.

I used to weight sort and do not find it adds much to the total time preparing bullets. I weighed each one on an electric scale and dropped it into a Dixie cup by .1 grain, just as easy as putting them altogether in a box. John and JoeB have convinced me that it was the wrong approach.

Now I first visually scan the bullet looking for flaws and complete fill out. When I am in my "casting groove" 95% will pass and I am picky. The I weigh them, because about 1% will have hidden a void that is about 2 grains (must be a flaw in my technique). Since they are already weighted, I sort by .1 grain any way. My weight curve is not a bell curve but a skinny pyramid. Total weight spread I will use in match really quite large, maybe .8 grains depending upon number needed.

And I have been loading them differently, The heaviest cup with at least five bullets are loaded as one set and used for a five shot match. When that weight is gone, I load the next heaviest cup. When I have 125 match loads for a two day match, all the rest are sighters.

 

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45 2.1 posted this 26 March 2020

There are a lot of anomalies when dealing with cast bullets. Just because they weigh the same doesn't mean they are the same. Once you have a good lot of the same weight bullet... measure them for diameter (on the same place on the bullet) and segregate that way also, then shoot them. I'll be waiting for either a confirmation or denial...............

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John Alexander posted this 27 March 2020

Ric,

I am interested in your finding 1% with a void.  I sure as heck would abandon my no weighing policy if I could find such a thing. I weighed tons of bullets before I gave it up and don't remember finding such a light bullet. I know most people weigh their bullets so are others finding very light bullets.

I have never found a bullet light enough to make me think it had a void but then i cast different sized bullets than most all of you.  I seldom cast for my heavy calibers like 6mm, the biggest bullet I normally cast is an 85 grain 22 caliber.  I assume the bigger the casting the more likely shrinkage voids so maybe that's the answer.

What about you BPCR shooters that cast those thumb sized bullets? Are voids a problem?  45-70s are popular how about casting for those?

John

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RicinYakima posted this 27 March 2020

45 2.1, I have been reading your replies the last couple of years and by reading between the lines, see what you are driving at. In fact I have a couple of sets of bullets to try the weight and size separation. However, it will be a while as WA is in lock down and with the range being a county park, no idea when it will open. Ric

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shootcast posted this 27 March 2020

The only printed literature that I have read states, well filled out bullets varying from the average weight by more than 0.2 grains should be considered a minor defect. Variation of more than 0.5 grains should be considered a major defect. However it doesn’t state that this should be used for all Bullet weights. If for example your casting 22 cal. Bullets and experience that amount you probably have done something really wrong. The above limits seem fine for 30 cal.heavy bullets. I would think that as Bullet weight and size increase so should the limits. And or decrease with smaller weight bullets.

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RicinYakima posted this 27 March 2020

John, All of my match bullets are cast from a pre 1912 Ideal mould #311284. Normal weight is about 215 grains. Since I read the article in Fouling Shot years ago about milling the bullets looking for voids I did the same. The voids are long thin ones off the centerline of the bullet and never reach the outside.

My hypothesis, not even a theory, is that I ladle pour my bullets in the winter in my shop. I used Linotype for years but am now using half and half monotype and WW's. I may letting my mould get too cold and the alloy solidifying before complete filling. Both of these alloys have a very short pasty phase. And being a cheap Scot, I hate to burn off tin out of my alloy!

I make about 400 bullets in a four hour session. After visual sort, maybe four or five will be 2+ grains light.

When I was shooting Big Bore military, I either shot 1/30 with no antimony, or linotype. WW's had bad void and fill problems for me with 500 grain moulds.

Ric

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45 2.1 posted this 27 March 2020

45 2.1, I have been reading your replies the last couple of years and by reading between the lines, see what you are driving at. In fact I have a couple of sets of bullets to try the weight and size separation. However, it will be a while as WA is in lock down and with the range being a county park, no idea when it will open. Ric

Try it..... no weight variation in the lot. A large lot should show diameter differences... sort by diameter (using a micrometer) into lots with a normal control lot picked out  before segregating to test against. This works better the smaller caliber bullet you shoot. With big 45 caliber 500 grain bullets the less well it works.

When I was shooting Big Bore military, I either shot 1/30 with no antimony, or linotype. WW's had bad void and fill problems for me with 500 grain moulds.

Some help: big bore militaries usually respond to much softer alloys when you want superior accuracy. This has been so for me using 50:1 lead to tin in the 50-70, 45-70, 40-50BN and 43 Mauser....... some naked and some were paper patched.

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45 2.1 posted this 27 March 2020

 What about you BPCR shooters that cast those thumb sized bullets? Are voids a problem?  45-70s are popular how about casting for those?

John

If you find voids, they are basically the same size in the same positions as on smaller bullets... at least that is what I've experienced before. It's easier to cast good bullets with a 45 caliber single cavity 500 grain mold than it is to cast the same with a 30 caliber mold though. And I've shot a whole lot of those big bullets through the years..........................

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fa38 posted this 27 March 2020

""I am interested in your finding 1% with a void.  I sure as heck would abandon my no weighing policy if I could find such a thing. I weighed tons of bullets before I gave it up and don't remember finding such a light bullet. I know most people weigh their bullets so are others finding very light bullets.

John""


I used to tumble coat my cast bullets with moly in a Thumlers tumbler with some BB’s purchased from NECO.  These were plain based bullets for my .30 and .32 caliber for my Schuetzen rifles.  All bullets were inspected for flaws before tumbling but not weighed. 


The tumbling did three things, one of them intended.  The intended purpose was to moly coat the bullet.  The unexpected things were the area slightly ahead of the base developed a small ring about 1 to 1.5 thousandths larger than the bullet diameter.  The other thing was that it would reveal voids that were close to the surface of the bullet by showing an indentation in the bullet surface that was not visible before tumbling. 

 

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RicinYakima posted this 27 March 2020

fa38, did you write the Fouling Shot article about that issue maybe 20 years ago?

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fa38 posted this 27 March 2020

I remember writing about it but do not know where I sent it. It could have been the ASSRA magazine. It could have been 30 or more years ago.

I first used the moly for my 30-30 x 1.5 inch with fixed ammo in a ISSA match in Eau Claire, WI where I actually took second place in the scope bench, last time that ever happened.  I think Clark Ehlers probably won the bench aggregate.  He usually kicks every bodies butt in bench at that ISSA match.  It worked quite well for me but was so messy, black stuff on everything, that I quit using it.

 

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Coydog posted this 27 March 2020

For me when I weight my rifle boolits I go with .5 +- and that is after I size and lube and GC. and use the most of the one for what I looking to do and then the rest for one of the other rifles I have in the same cal but different round,that is 30cal. 

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John Alexander posted this 27 March 2020

Ric asked: "fa38, did you write the Fouling Shot article about that issue maybe 20 years ago?

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You may be thinking about an article by Bob Birmley about 10 -- 12  years ago in which he described how tumbling exposed lots of surface  voids.  Very much like fa38 found although he didn't say anything about tumbling cause a ring.  He had beautiful pictures and claimed that after sorting out bullets with the surface bubbles his groups improved with his heavy class rifle which was shooting groups close to .5 MOA. Very well written article.

A few years later when I mentioned to him that it was an excellent article he said that he had since modified his casting procedures and completely eliminated the surface bubbles and no longer needed to tumble to find them.  Unfortunately, he hasn't written a follow up article to tell the rest of the story.

A couple of months ago on the ASSRA forum there was a discussion about Bob's  article and the existence of these sneaky hidden voids but they didn't know he had found a way to eliminate  them.  I don't know exactly either since he didn't say in our conversation.

John 

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fa38 posted this 27 March 2020

 

I noticed the ring after I decided to run some bullets thru my lube sizer to see if the lube would make a difference in grouping.  The sizing die would make that ring shiny.

I think the ring came about when the bullet would drop base first in the tumbler. That tumbler is an octagon and I think the bullets carried up on a flat and then dropped onto other bullets or the hardened shot.

 

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shuz44 posted this 27 March 2020

For those that shoot the cast bullet benchrest matches, I would assume you weigh each bullet after casting to cull those out of.........? So my question is, how much plus-minus do you keep?

I don't go too crazy, I just use my chargemaster to weigh each bullet. I make a pile of each per tenth of a grain, and see how they play out. To me, I pick the "middle" weight, then give 2 tenths plus and minus, for my 200 yard bullets. Depending on how they all weigh out, I give a little more variance to shoot 100 yards.

The bullets that are out of the "good", I keep and powder coat those a different color and use for fowlers after cleaning the barrel.

As a bit of an aside, on another thread, it was asked about GC before or after PC. I seat before, I use a seater I made that is drilled and reamed to bullet size, with a small cut for the GC in the bottom. I seat the GC using an arbor press, then shake and bake. Never had a GC come off.

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shuz44 posted this 27 March 2020

Sorry fellows, I'm not sure how to post correctly. Can some one tell me....If I wanna Reply to a POST DO I HAVE TO SCROLL TO THE BOTTOM AND HIT "ADD POST" hELP sorry BOUT THE CAPLOCK key my fumble fingers hit the darn thing all the time. 

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4and1 posted this 27 March 2020

Are you logged into your account? If you're not logged on, you can read everything but not reply. If you're logged on, at the bottom of a post you should see Like, Favorite, Is Solution, and Reply. Click on reply.

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shuz44 posted this 27 March 2020

Thank you. I got it now, I think!

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