Square bullet bases

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  • Last Post 30 March 2009
Tom Acheson posted this 16 March 2009

Finally a break in the weather and an opportunity to get out in the garage and do some casting. I was running two moulds at the same time and two pots (a different alloy in each). One mould was a plain base and the other a gas check design.

I know the need for a square base on the plain base bullet. However, does the same demand for the squareness of bases exist for a gas check design bullets since we'll be covering-up the base with a gas check? Those of us who “bump” our bullets apply a really square base during that step. Has anyone ever done an exhaustive test to verify the differences if any between absolutely square and “almost” square bases when used with gas checks?

Just curious. Your mind will sometimes wander and cause you to question your long held “rules of thumb” regarding casting.

Thanks!

Tom

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billwnr posted this 16 March 2009

I suppose the almost square bases would work real good if they were uniformly almost square.

I know how almost square bases shoot in my 1903 Springfield and I don't notice any difference between them and bullets with square bases that have been tapered. This is with the legal 6X scope as I haven't shot with a higher power.

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mrbill2 posted this 16 March 2009

I had gotten a hold of some Lyman 311467 bullets one time with the bases almost square, plus other flaws. If I had been making them they would have been remelted. But just to see how they would shoot I loaded some anyway. Well they shot 1 1/2 at one hundred. Go Figure. I still like square bases. Mr. Bill2

mrbill2

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CB posted this 16 March 2009

I certainly wouldn't call my testing on this question exhaustive but I have shot alternate groups with square based and rounded bases several times  and the rounded bases shot better about half the time so I am skeptical that it makes any difference.  None of these were bumped.

I am talking about groups that average about one MOA for five shots so I don't know if you could tell the difference if you were at the 1/2 MOA level.  All my testing was with long 22 caliber bullets.

I am always amazed at guys throwing a good share of their bullets back because of minor defects when they are shooting rifles that won't shoot under 2 MOA or worse yet pistol shooters going for “perfect” bullets.  Of course this is a hobby so if you just like pretty bullets go for it, but I think a lot of new shooters put up with a lot of extra work and worry about something that doesn't improve performance. John

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CB posted this 16 March 2009

I think the quest for the perfect bullet is one to satisfy ones comfort level and confidence in the bullet. You can have a bullet that by most sense is quite shootable, but if your confidence in that bullet is poor, then the accuracy will be poor.

I made some bullets for a match this coming weekend that are passable, but I really should have remelted them to suit my comfort and confidence. My wife will be shooting them and since she doesnt know any better I will be able to see if they in fact shoot better or worse. She is a pretty fair shot, shoots in the high 380's all of the time, we will see how she does with these bullets and then maybe there will be something to ponder over.

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RicinYakima posted this 16 March 2009

Jeff Bowles wrote: I think the quest for the perfect bullet is one to satisfy ones comfort level and confidence in the bullet.  Jeff, I agree totally with this! If there is a bad shot, I want to know that it is me that made the error, not the load. Ric

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linoww posted this 17 March 2009

"Has anyone ever done an exhaustive test to verify the differences if any between absolutely square and “almost” square bases when used with gas checks?"

I have always wondered that as well.

I had some SAECO #315 bullets that i got in a hurry casting that had very bad sprue bumps.I set them aside for awhile then needed some bullets to shoot so i loaded them up.When looking at the GC is actually was not always perfectly square with the bullet body!!Surprisingly they shot just as well as the good based bullets.The gun i was using was a military 1903 with peep sight so 1.5 MOA is tops for that gun and possibly i would have seen the difference in a more accurate rifle.Now if i have a known load that shoots i am less likely to toss bump based bullet for practice.The wind conditions and how i am seeing the sights seems to be more important in my sprue bump deal.When testing a new load and bullet i am pretty careful segregating bullets though.

I agree with John A. that fussing about perfect bullets(weighing, gauging etc.) will take away range time to learn how to handle the rifle and load,but they at least have to be uniform and well filled out.

George

"if it was easy we'd let women do it" don't tell my wife I said that!

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runfiverun posted this 17 March 2009

funny, i was pondering this too.

the ones with the slightly rounded edges seem to have sharper edges everywhere else.

i am thinking the g/c covers this part up ,and the weight difference is the only thing that would be different..

you might get that much difference in the lube missing a spot.

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runfiverun posted this 17 March 2009

funny, i was pondering this too.

the ones with the slightly rounded edges seem to have sharper edges everywhere else.

i am thinking the g/c covers this part up ,and the weight difference is the only thing that would be different..

you might get that much difference in the lube missing a spot.

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jimkim posted this 17 March 2009

I'm gonna go out on a limb and say every one of us has been wondering about this one. The bullets my Ranch Dog mould drop seem to come out with two different bases. One cavity drops rounded and one drops square bases. I think the rounded ones fit the GC's better and may seat more squarely. Does anyone make a GC's shank uniformer/sizer? I may have to build one.

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KenK posted this 17 March 2009

On the one hand; I cull every flawed bullet I see, on the other hand, I don't look at them very hard. : )

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mrbill2 posted this 17 March 2009

Well I to wondered about those little bumps. So I made a little collet so that I could remove the bumps and square the bullet base in the lathe. The GC shank uniformer/sizer worked. After shooting quite a number with and without bumps it was plain to see, what a lousy shot I can be. I didn't prove anything.

Mr. Bill 

 

jimkim wrote: I'm gonna go out on a limb and say every one of us has been wondering about this one. The bullets my Ranch Dog mould drop seem to come out with two different bases. One cavity drops rounded and one drops square bases. I think the rounded ones fit the GC's better and may seat more squarely. Does anyone make a GC's shank uniformer/sizer? I may have to build one.

mrbill2

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CB posted this 17 March 2009

Now for a different train of thought here. Since cast bullets are elastic, and are known to obturate to fit the bore, would it make sense to assume that the bullet base, which is also elastic, might not deform to be squarely perpendicular with the bore under enough chamber pressure to cause bullet obturation?

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jhalcott posted this 17 March 2009

Anachronism, THAT is an idea that I have had for quite a few years! It would seem to work IF the pressure is high at the moment the slug starts to move. It may NOT work as well if you are using a slow powder that takes a few inches of bore to reach max pressure.Then all this would depend on alloy hardness too, wouldn't it?

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CB posted this 18 March 2009

"Now for a different train of thought here. Since cast bullets are elastic, and are known to obturate to fit the bore, would it make sense to assume that the bullet base, which is also elastic, might not deform to be squarely perpendicular with the bore under enough chamber pressure to cause bullet obturation?"

If by obturation you mean the bullet shortens and swells up (upsets is the engineering term), which is a common, but not proven belief, then you might be interested in Ken Mollohan's article based on a lot of testing which failed to find that this actually happens with cast rifle bullets of reasonable hardness. Ken's article was in the September/October issue of the Fouling Shot.

We like to think of rifle bullets squishing up to fill the throat and bore, but Ken found that they don't. I have never seen a similar article that found they do by any tests.

It would be very interesting if someone would would catch enough bullets,without deforming them, of varying hardness and shot at high velocity and see if they could PROVE that bullets upset and disprove Ken's findings.

John

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KenK posted this 18 March 2009

I have recovered bullets, with a bore ride nose that fit very loosely in the bore, that were engraved by all lands of the rifling for maybe a quarter of the length of the nose.

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Dale53 posted this 18 March 2009

I have a bit different take on the “flawed” bullets. I cast nice bullets because I can. I have learned how to do it. I am pretty dern particular with my bullets and recast any that “don't make the cut".

I am shooting mostly revolvers these days due to vision problems (Red Dots allow me to shoot my best in spite of poor vision). However, I cast my revolver bullets as if I were shooting them in my ½ minute Schuetzen Rifle. The only difference is that I use multi cavity moulds and I only occasionally weigh a few for quality checks. I DO weigh my Schuetzen bullets. I, a couple of days ago, cast 1000 .38 wadcutter bullets and only discarded 17 of them while sizing. They were cast in a six cavity H&G #251 mould (dbl ended w/c). Like I say, I am pretty dern particular and BASES is what is most important to me. Ransom Rest tests have convinced me.

My theory is based on the statisticians statement that the error of the ammunition is ADDED to the error of the shooter. I accept that and conduct my bullet casting accordingly. Frankly, it takes little longer to do it right than not. I am NOT a super hero bullet casting whiz - I just do the best that I can and my best is pretty dern good(:>)).

Dale53

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CB posted this 20 March 2009

Perhaps if water-caught bullets could be obtained that haven't been deformed by impact (abandon hope), it might be possible to measure the relationship between the base & the bullet shank before and after firing, to see if there is any difference. So many factors would come into play here so as to stagger the imagination. Everything would be on the table, and subject to scrutiny. After playing around with black powder for a few years, I'm not ready to just come out accept that cast bullets don't obturate, and this is not meant to be any kind of judgement on Kens article. I'd never do that to anyone.

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CB posted this 22 March 2009

<"I am pretty dern particular and BASES is what is most important to me. Ransom Rest tests have convinced me.>"

Dale53,

It would be great if you wrote up the results of your Ransom Rest tests, for the Fouling Shot or this forum, showing that rounded bases degrade accuracy and how bad the rounding has to be to show a difference, since so many of us have found the opposite often at higher accuracy levels than expected from pistols.

John

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CB posted this 22 March 2009

<' I have recovered bullets, with a bore ride nose that fit very loosely in the bore, that were engraved by all lands of the rifling for maybe a quarter of the length of the nose.">

KenK,

Very interesting.  That certainly is evidence that some bullets do upset to fill the bore.  How hard were the bullets and how fast were you pushing them?

How did your bullets and loads compare to the ones Ken M. reported on in the FS?

John

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TRKakaCatWhisperer posted this 22 March 2009

alexanderj wrote: ...If by obturation you mean the bullet shortens and swells up (upsets is the engineering term), which is a common, but not proven belief, then you might be interested in Ken Mollohan's article based on a lot of testing which failed to find that this actually happens with cast rifle bullets of reasonable hardness. Ken's article was in the September/October issue of the Fouling Shot.

... John

Check out Dr. Franklin Mann's volume “The Bullet's Flight” published in the '20's.  With soft lead bullets they start deforming immediately.  Many many pictures from several experiments.

 

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CB posted this 22 March 2009

Well we shot that match in which my wife shot those not so great in my opinion bullets. It was difficult to say whether the bullets affected the accuracy or was it the goofy winds that day. I will say this much. She did not practice. It was her first match since last October. She shot the smallest group of the day. She shot lower than normal scores on the score targets. What did this prove. It proved my wife can get pretty darn cranky when she doesn't shoot well and I beat her heavy BR gun with a Savage M12 in production class.

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Tom Acheson posted this 23 March 2009

So if we convince ourselves that the squareness of the base is a key to good accuracy, we can get tempted to want to use the Hoch and Eagan type nose pour moulds to achieve the optimum base condition. But somewhere, way back in the memory banks, I can recall someone opining that the majority of the “internal defects” of a CB are in the bottom of the mould as we pour. So IF that is true, does the nose pour mould result in potentially being less accurate than a traditional base pour mould because of the chance that the defect will be farther out from the bullet's axis and cause more of a disturbed flight?

Tom

 

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TRKakaCatWhisperer posted this 23 March 2009

Tom Acheson wrote: ... However, does the same demand for the squareness of bases exist for a gas check design bullets since we'll be covering-up the base with a gas check? ...Tom

Dr Mann did some interesting tests or experiments to determine WHAT effects were important.

With plain based bullets (I'm suggesting this coult be replicated with gas-check bullets, which would answer your question) he 'deformed' various parts of the bullet. With the bases he noticed that if the 'deformity' was oriented randomly that the group was large; however if the deformity was oriented to a paritcular direction, after the bullet got to the muzzle it exited with that deformity oriented offset by the rotation the length of the barrel AND that the group was smaller and offset in some direction (based on the distance and the length of the barrel).

One COULD take some gas checks and file a bevel on one side and then orient them and fire several groups as Dr Mann did with plain based bullets.  It might take 50 or 100 rounds and the answer would be documented for the rest of the cast bullet society to review and see if the results could be replicated. 

It's called research.

 

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CB posted this 25 March 2009

TRK wrote: alexanderj wrote: ...If by obturation you mean the bullet shortens and swells up (upsets is the engineering term), which is a common, but not proven belief, then you might be interested in Ken Mollohan's article based on a lot of testing which failed to find that this actually happens with cast rifle bullets of reasonable hardness. Ken's article was in the September/October issue of the Fouling Shot.

John

Check out Dr. Franklin Mann's volume “The Bullet's Flight” published in the '20's.  With soft lead bullets they start deforming immediately.  Many many pictures from several experiments.

TRK A classic apples and oranges situation.  There is no doubt that soft lead bullets upset.  An old Am.Rifleman article, back when they had interesting articles, reported on shooting a revolver with soft bullets without the barrel and catching the bullets.  They were practically mushroomed on the rear.

If I understood the article Ken M's bullets were all fairly hard like most of us shoot in smokless powder rifle loads ( maybe over BHN of 15 or so).  Ken examined lots of bullets and found none that had upset.  It would be a good contribution to find out at what pressure for what alloy upset starts.  We may be kidding ourselves if we just assume that the bullet always upsets and helps keep the hot gas behind the bullet.

So if upset for reasonably hard bullets has been proven, I have never seen the report of such tests.  Dr. Mann's work certainly didn't do it because his work was with soft bullets.

John

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KenK posted this 25 March 2009

I always assumed that the vast majority of cast bullet shooters were shooting wheel weight bullets, or various other scrap.

My earlier post about the bore ride nose being engraved was in fact with a ww and tin bullet.

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JetMech posted this 25 March 2009

20 years ago, WW were softer, as are some truck weights I have, about 9 BHN. Now the typical WW runs about 12 BHN a couple days after I cast ingots. Add a little tin and I think your right at the point where a bullet may or not upset at typical pressures we run to produce velocities in the 1200-1600 fps range. 

As far as bases are concerned, it's well known that the air behind a moving object affects the movement of that object. Just look at a NASCAR race. When 2 cars draft together, they both move faster. The air directly behind the bullet is a low pressure area. As long as that area is round and consistant, it won't affect the direction of travel of the bullet. but introduce a flaw, and that low pressure area becomes disturbed. If one part of the base has different air pressure, the bullet will yaw towards the low pressure side. That could explain Mann's experiments that showed a bullet corkscrews thru the air. It's yawing towards that low pressure side, which is also rotating at high speed.

As to whether it makes enough of a difference to matter, not that I've been able to tell. But with a true bench gun and the capabilities some of you guys have, it very well may. But not in my “minute of deer” rifle.

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TRKakaCatWhisperer posted this 29 March 2009

alexanderj wrote: ... So if upset for reasonably hard bullets has been proven, I have never seen the report of such tests.  Dr. Mann's work certainly didn't do it because his work was with soft bullets.

John

Dr Mann's work proved the principle, verified later by others.  The question, then, is one of degree.  At some point of pressure (hence acceleration) and some point of hardness the deformation changes from inelastic to elastic.  What then, is where that point is?  What then is 'proof'.  Measure the diameter of the nose-riding portion before and after firing - easy enough to do in controlled tests.  Vary the hardness and charges.  Put numbers with units to the term “reasonably hard".

 

 

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Cary posted this 30 March 2009

Tom Acheson wrote: Finally a break in the weather and an opportunity to get out in the garage and do some casting. I was running two moulds at the same time and two pots (a different alloy in each). One mould was a plain base and the other a gas check design.

I know the need for a square base on the plain base bullet. However, does the same demand for the squareness of bases exist for a gas check design bullets since we'll be covering-up the base with a gas check? Those of us who “bump” our bullets apply a really square base during that step. Has anyone ever done an exhaustive test to verify the differences if any between absolutely square and “almost” square bases when used with gas checks?

Just curious. Your mind will sometimes wander and cause you to question your long held “rules of thumb” regarding casting.

Thanks!Some interesting concepts and information in this topic. I am fairly new to this forum but not to casting. I do have a question. You mention bumping bullets to square the bullet base. What is your procedure for doing this? Are any special tools required? Cary

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Notlwonk posted this 30 March 2009

jimkim wrote: . The bullets my Ranch Dog mould drop seem to come out with two different bases. One cavity drops rounded and one drops square bases. I think the rounded ones fit the GC's better and may seat more squarely. .

This makes sense, the inside of the GC has a radius and the sharp cornered bullet has to 'deform' evenly or otherwise when seating the GC.

As to the round base vs sharp cornered base accuracy, somewhere years ago I read an article about this very thing. The sharp cornered bullets formed fins at the lands and this impaired accuracy.  

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