What is the Most Promising Aspect of CB Rifle Shooting for Improving Accuracy?

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John Alexander posted this 18 January 2020

CBA has been partially responsible for the progress we have made in shooting CBs in fixed ammunition (as opposed to breech seating) over the last forty years but that progress has mostly stopped.  Those shooting specialized custom rifles with no restrictions cannot consistently shoot aggregates of 5-shot groups much under 0.5" at 100 yards.  Those of us who like to shoot unmodified factory or old military rifles cannot consistently shoot 5-shot aggregates much under 1.0" at 100 yards. We have been able to shoot to this level of accuracy for at least ten and maybe twenty years with little improvement.

The first of the four stated "purposes" of the CBA on the back of every Fouling Shot says: encouraging experiments that will improve the accuracy and effectiveness of the ammunition and increase the satisfaction and enjoyment of shooters. Many, probably most, of us that shoot CBs in rifles want to improve either to enhance our competitiveness if we like to shoot in matches or simple to do better for field use or personal satisfaction if we don't. 

What is the best way to achieve that improvement?  Up until now many have thought that uniformity was the road to improvement.  Ever more uniform weights of cases, powder, bullets, even gas checks and primers, ever more uniform sizes of bullets, flash holes, primer pockets, ever more cleanliness of bores, case necks, primer pockets and inside cases. Other efforts at improving uniformity have included using only one case, using nose pour molds or turning bases to achieve perfect bases, shooting bullets in the order they were cast, indexing bullets, cases and even primers.

It is hard to argue against uniformity but easy to see that more and more isn't always better and some of the above have been grossly overdone and achieved nothing.  Many of our best shooters have found many of the extreme attempts for uniformity listed above were worthless and have abandoned them. 

Paul Pollard has asked in the thread on factory ammunition what should we be working on to improve?

Because we have already tried pursuing uniformity to the point of foolishness, that approach doesn't look promising for future improvements. I hope we can start a discussion on what are some of the promising ways that should be explored in order to shoot CBs more accurately? What do you think?

John

 

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4and1 posted this 04 March 2020

I'm fairly new to cast bullet benchrest. I do however have over 25 years of shooting both score and group benchrest with jacketed bullets. I have competed against the top shooters in this country (note I said competed against, not beat!). We all have guns that have the best of the best gun components, we use the best of the best ammo components. So why do some always end up at the top of the results and most are below them? Those at the top know how to keep a gun in tune. They change their loads from the first warmup match to the last target of the day. They know how to deal with temperature changes and humidity changes. Those here that have that some days you do good and the next day not so much. Well there is your reason.

But, one thing is a given. You cannot tune a gun, you cannot properly hold off from the last shot on paper, unless you KNOW your last bullet shot where it should have. What I mean is, if it were a flier and you took that as full value, your next shot based on that one will be wrong. You can't have UNEXPLAINED fliers and shoot a great match. If a shot goes out of your group, you have to know it was a missed condition, not a bad bullet.

I agree with all here that believe bullets are the biggest culprit to inaccuracy. I swage my own jacketed bullets. The cores must be pure in their alloy since they are squirted by size/volume. The jackets must have very little to no wall thickness variance (.0003" or less). And your dies must be good, they all are not made equal. The process and lube in swaging must be the same. Good bullets fly true, a flier is caused by conditions or out of tune load.

So in my opinion, it's the bullets, assuming the gun is capable.

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45 2.1 posted this 19 January 2020

45 2.1 said: Wait at least two weeks until you size them

I probably need to go back to bullet casting school, but what is the importance of the 2 week waiting period before sizing? Does the bullet retain its size better at this time instead of sizing the same day?

Thanks

Antimony dendrite growth......... Antimony grows a lattice structure as long as the Tin content is a lot lower than the antimony content. While doing that it also gets a little larger and harder. You need to wait for it to slow down and stabilize some. Of course the longer you wait the better they usually shoot.

 

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shootcast posted this 19 January 2020

I agree with Tom that on any given day there are always conditions that effect our ability. These range conditions probably have more to do with it than any other factor. How many times have you worked up a particular combination, alloy, Bullet , lube, powder charge and overall cartridge length. You think you found the best possible combination it shoots very well. So when you go home you duplicate everything to the best of your ability. Same alloy, same loading process. After all you wrote everything down. Next trip to the club or worse yet the match and everything changes. Imagine that ! . 

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John Alexander posted this 20 January 2020

shootcast points out: "You think you found the best possible combination it shoots very well. So when you go home you duplicate everything to the best of your ability. Same alloy, same loading process. After all you wrote everything down. Next trip to the club or worse yet the match and everything changes. Imagine that !.

++++++++++

Most of us have had similar experiences.  To some extent these experiences show us that we have more to learn about how conditions (temperature, wind, mirage, humidity, elevation, phase of the moon) affect our groups.

More often I suspect it shows  that we don't shoot as well some days as on others. I know that in spite of my practice, dry firing, etc. I don't.

Perhaps even more likely than either of the above it may simply be the large natural variation between groups (even when everything is identical) has led us to a false conclusion. We tend to forget, or refuse to believe, that in a string of five 5-shot groups the largest group will be twice as big as the smallest almost half the time.  So if you are making a judgement by looking at single five shot groups, or even a few, those groups may easily be much bigger than average -- or much smaller, leading to wrong conclusions. Of course this doesn't apply if you are comparing one match, or a many group session to another.

FWIW

John

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JimmyDee posted this 25 February 2020

I keep wanting to remark on cases and preparation.

I saw a video of a man shooting 30BR on an indoor range.  Using one case, an electronic annealing device, careful technique, a sled gun, and an armful of computers and electronics and cameras, successive shots had *identical* muzzle velocities and barely fuzzed the edges of a hole on a paper target.

I remember a long-range shooter remarking that the first loading using new, carefully prepared brass consistently produced the best groups.  Reloading - as opposed to selling once-fired brass and buying new - saved him only $.05 per round and produced larger groups.  (He must have been getting a good price for his used brass.)

But the OP asked about the most promising precision improvement.  I have to agree with others that changing the projectile material would give the greatest improvement.  Soft alloy produces larger groups than linotype which produces larger groups than jacketed; harder seems better.

Cast bullets are what we're all about but we're not talking about cast bronze or cast iron; we're talking about metals that melt at low temperatures -- like lead, tin, bismuth, zinc, and indium.  Even antimony, common in many bullet alloys, has a melting point that's hard to attain at home and is usually bought as alloy that melts at a lower temperature.

While various zinc bullets seem to produce good groups, RickInYakama points out that downrange performance suffers -- although maybe not on indoor 100 yard ranges.  Sectional density matters.  Monotype and linotype are fine for target applications but are poor performers on game.

I don't think we can realistically improve cast bullet alloy very much and I think we have a good understanding of alloys and their application.  We know about bullet designs suitable for modern lube that fill throats and match centers of gravity and pressure.

So, what's next?  Is it cases?  Did I just walk in a circle?

 

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RicinYakima posted this 18 January 2020

IMHO, a better material to make the bullets out of besides lead. As a new guy only doing this for about 24 years, I have followed every thread I could find plus reading every book I could find back to the 1890's. We seem to have reached the point that our lead alloys are not capable of handling the stress of being a bullet and fired more accurately. The leaders of the lead-free movement are looking at home castable bullets that do not contain lead. That is really unexplored territory.

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joeb33050 posted this 18 January 2020

IT'S THE BULLETS!!!!!!!!!!!!!!

ZINC?

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Larry Gibson posted this 18 January 2020

I believe Joe is correct....it is the bullet.  Understanding that imbalances in the bullet during the external ballistic phase (bullet flight) are the reason we shoot groups instead of all going into the same hole.  In flight, if the center of form, center of gravity and center of spin do not coincide in the longitudinal axis then the bullets will vary from the intended flight path...i.e. shoot groups.  Then we also have the center of pressure and it's relation to the center of gravity and center of form in the lateral spectrum.

We can do all the things John mentions to ensure our cast bullets are about as perfect and consistent as possible.  However, we can not control exactly the balance of the difference metals during solidification or the control slight differences in the shrinkage during solidification.  Thus there will always be slight imbalances in the bullet no matter how well we think we cast.  We can not control the precise loss of lube on exit from the muzzle and during flight.  Then are we sure the GC is really consistent and balanced or do we just assume it is(?).  Additionally we can not control precisely the unbalancing affect acceleration has on the bullet during the internal ballistic phase.  Perhaps it's just the nature of a cast bullet and we've just not accepted that(?).

An occasional really small group will be shot now and then when the Sun, the Moon and stars all line up...…. but to consistently shoot such really small groups may not be in the cards.  Those really small groups John and everyone else searches for are anomalies...…...not saying we should quit searching for an answer but the question of just how consistently accurate (or precision) can we shoot cast bullets may already have answered.....

LMG

 

Concealment is not cover.........

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RicinYakima posted this 26 January 2020

"Zamak" is a trade name for a groups of zinc based alloys, with aluminum, tin and copper mostly. I became familiar with it in the 1950's as the metal used to make the bodies of auto carburetors, fuel pumps and other low stress parts. In the '70's I would go to the junk yards and they would give me a bucket of broken fuel pumps for $.50. I'd break them apart and cast "bullets" out of them. The problem is that once you cast a bullet with this stuff, the mould will never cast lead again. And the pot you used will have to be cleaned down to the bare metal!

You could shoot .357's really fast for the first 25 yards. With no weight in the bullet, drop was a problem at 50 yards. If we want to use another metal, it has to have a lot higher density than zinc. While it is "hard", it will never conform to the bore and always leak gas around the sides. Lyman made specific bullet moulds for this metal in the 1950's.

Maybe someone has more experience than I have?

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M3 Mitch posted this 25 February 2020

Funny you would mention cases, JimmyDee, I was just here to point out that I have heard, but have not actually tested for myself, that one of the easiest accuracy enhancements available is to buy some premium brass, stuff like Lapua and Norma.  For some reason the Scandinavian brass makers make a superior product, of course it costs more, but is more consistent.

The whole accuracy game is hard to understand from a theoretical standpoint.  What I mean is, things that "common sense" would suggest ought to matter, like sorting bullets by weight, or weighing individual powder charges, don't actually help much in the real world. 

What apparently matters the most, is to have a bullet that is at the right hardness and not undersized.  A bullet can be pretty far oversized and this, in my experience and from what I read, does not matter near as much as undersized.  I think the vast majority of leading experienced with *cast* bullets is due to undersized bullets that are too hard to obtruate and seal the bore. So an undersized bullet is the key to inaccuracy.  If I could only find some one point that would give accuracy so easily.

For practical matters, particularly cast bullet hunting, for most of us, even a 2" group at 100 yards is very adequate for the ranges we have to stay within given that even a #2 alloy bullet is not the equal of a decent jacketed soft point, and substantially inferior to something like a Nosler Partition. 

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John Alexander posted this 25 February 2020

JimmyDee mentions: " Soft alloy produces larger groups than linotype which produces larger groups than jacketed; harder seems better."

===========

Before we run too far with this idea that harder is always better I respectfully point out that there is no significant difference in the match performance of CBA Heavy and Unrestricted class usually using linotype and PBB class that uses 25:1 and softer.  There are even a few oddballs shooting fixed ammunition that do well with the very soft alloys shooting against others using linotype. So darned many factors involved.

M3 Mitch writes: "I have heard, but have not actually tested for myself, that one of the easiest accuracy enhancements available is to buy some premium brass, stuff like Lapua and Norma."

=====

I use Lapua or Norma brass wherever I can, just in case it make a difference.  It is more consistent in neck thickness and weight than the domestic brass I have at least. However, I have never been able to prove that it helps accuracy a bit.   Does anybody know of any well run tests that show the more consistent  brass improves accuracy?

Do we even actually know that "prepping" cases actually improves accuracy?

So many questions -- so many opinions -- so little experimentation to see if the opinions are worth what they cost.

John

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Tom G posted this 27 February 2020

We can blame poor accuracy on all kinds of different reasons but my experience has shown that cast bullets just don't shoot as well in a particular rifle as match grade or even so so jacketed bullets. This tells me that it's something to do with the bullets and not the guns or the shooting technique or the guy behind the trigger. 

Sure, none of us have exactly the same level of skill as the others when it comes to shooting. But, when you build a first class benchrest rifle, put a 36 power scope on it., shoot it on a first class bench in good shooting conditions, if you get poor groups, it pretty much boils down to something to do with the bullets we shoot. Shooting off the bench with a flat fore end rifle on a front rest with proper bags and a 2 oz. trigger takes a lot of the personal skill out of the reason why cast bullets don't shoot much better than a half minute of angle. 

I've shot thousands of rounds with cast bullets over 30 years and they never shoot as good as good jacketed bullets in the same gun. I have a Rem. 788 in 30-30 that shoots 7/8 moa consistently with cast bullets. One day I shot a bunch of 150 gr. jacketed bullets and worked up a good load. This gun shot half inch groups with just run of the mill production hollow point jacketed bullets. I have no doubt that it can shoot even better with match grade bullets. Before I shot the jacketed bullets I shot a series of groups with cast bullets that averaged just under one MOA. 

I was using the exact same equipment on the same range under the same conditions for this test. Nothing changed but the load. The results were consistent and repeatable. I shot lots of groups so it wasn't any kind of an abberation or fluke. 

The cast bullets I shot were all very good quality. The were very uniform and weighed just as close to each other as the jacketed bullets. They fit the barrel properly and were bumped in a taper die that fit the taper of the throat of the gun. The bases were gas checked and bumped perfectly square to the c/l of the bullets. They should have shot into .3 moa in my estimation.  But they didn't, while so so jacketed bullets did shoot way under a half inch. groups. 

I've come to believe after many years of shooting cast bullets that the reason cast bullets are not as consistent as jacketed is a lack of a consistent barrel condition. By that I don't mean that this is caused by leading because my loads didn't lead at all. After a lot of soul searching and some more testing, I came to the conclusion that the lubricants that we use are the reason we can't shoot as good with cast as jacketed. 

In other words, the friction in the barrel and possible the gas blow by varies from one shot to the next and this caused the bullet to emit from the barrel at a different time during the barrel vibration cycles. I know from testing and have confirmed to my own satisfaction that the amount of lube on the bullet greatly effects what we call fliers. I also know from testing that the actual lube formula has a great effect on accuracy. By "great effect" I mean adding a quarter of an inch to a half inch to the group sizes.  To some, that amount may be inconsiquential but for a benchrest shooter it is a lot. 

Lube is the one variable in our loads that we have never really gotten a real hold on. If we ever get one that works perfectly, I think we can shoot cast bullets just as good and probably even better than jacketed bullets. 

In the past I've identified the fact that lube causes fliers. It's a necessary evil at this point in time if we want to shoot cast bullets without leading at any kind of higher velocity. So far, I've never been able to lick the flier problem but I've been able to reduce the fliers by playing around with the lube formula and the amount of lube on the bullets to get rid of about 90% of them. My theory, and it's only a theory since we can't see whats going on inside our barrels with each shot, is that the problem is that we cannot maintain a consistent level of lube and thus, friction and sealing over a long period of time. That the lube builds up in the barrel and every once in a while, it purges it out and the barrel goes back to a steady state for a few shots before the lube builds up again and gets to the point of causing bullets to fly out of the groups. 

I can cite examples of this happening. but this is already a long post. I can say that my suppositions are based on real observations of cause and effect. Not being able to monitor bore conditions as well as we would like, that's about all we can use to try to rationalize why we get fliers with cast bullets and don't with jacketed. 

It just snowed 6 inches last night and the wind is blowing so that the wind chill here is 8 degrees. I figured that this is a good time to throw out this theory and see how others feel about it. I think that the next big leap forward in cast bullet accuracy will undoubtebly be tied to finding or eliminating the use of converntional lubes as we know them. Flame on!! 

Tom Gray in snowy Michigan

 

 

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joeb33050 posted this 29 February 2020

 

If you're talking abouit under .4; then CBA NM:

 

 

 

 

 

But with cast you can do just about 0.3 MOA with a correctly fitting bullet alloyed for the load. Even a couple of long bodied Lyman numbers will do that when loaded right. 

=======

45 2.1 is right it is no big deal to shoot 0.3 moa with cast even I have done it with my hunting rifle.  There are usually a bunch of such groups at every CBA nationals. And of course its not rare on the Internet.  But a 0.5 moa aggregated will almost always take the gold in any cast bullet match anywhere and in the history of Am. Rifleman testing of a lot of high priced rifles I can't remember them every having achieved a 0.3 moa average and they are testing with several brands of jacketed bullet ammo -- funny abut that.

John

 

 

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David Reiss posted this 18 January 2020

I think the new coating is one aspect that has not been fully explored. We are just starting to experiment with the PCs, but true data under scientific conditions has not been done. Dan Lynch at Mountain Molds has been experimenting with different coatings with some success at high velocities. 

It is easy to believe there are many more coatings out there just waiting to be tried.

David Reiss - NRA Life Member & PSC Range Member Retired Police Firearms Instructor/Armorer
-Services: Wars Fought, Uprisings Quelled, Bars Emptied, Revolutions Started, Tigers Tamed, Assassinations Plotted, Women Seduced, Governments Run, Gun Appraisals, Lost Treasure Found.
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45 2.1 posted this 18 January 2020

CBA has been partially responsible for the progress we have made in shooting CBs in fixed ammunition (as opposed to breech seating) over the last forty years but that progress has mostly stopped.  Those shooting specialized custom rifles with no restrictions cannot consistently shoot aggregates of 5-shot groups much under 0.5" at 100 yards.  Those of us who like to shoot unmodified factory or old military rifles cannot consistently shoot 5-shot aggregates much under 1.0" at 100 yards. We have been able to shoot to this level of accuracy for at least ten and maybe twenty years with little improvement.

Granted, that we would be the CBA shooters in CBA matches. That leaves a large void you don't take into account and that doesn't include me either.


Because we have already tried pursuing uniformity to the point of foolishness, that approach doesn't look promising for future improvements. Correct! I hope we can start a discussion on what are some of the promising ways that should be explored in order to shoot CBs more accurately? What do you think?

John

 First of all, you all have tried the commercial bullets till everyone who does better has modified them in some way to do so. Most commercial bullets are undersize until they are fully in the barrel. If you are intent on shooting them, you need to use a soft alloy and a powder with a soft push and long pressure curve to get them in the barrel straight.

You need to try something else than what you are doing.... like a custom design and an alloy suitable to the load level you're trying. Harder is NOT better even though you guys really like linotype, it just isn't delivering great groups.

For you 308 shooters, I will give you a recipe for success. Try this alloy: 1/2 wheelweights with 1/2 dead soft lead (recovered factory wadcutters work fine) cast at about 725 degrees with a pot and ladle. Do not add anything to it! The sprue should set in about 3.5 to 4 seconds. Adjust the temperature until it does. Once there water drop them. Wait at least two weeks until you size them at 0.311" with Hornady gas checks with a "low viscosity lube" (that's important). The mold to use is this: https://www.mp-molds.com/product/mp-308-hunting-hp-gc/ with the hollow point pins. That bullet is dynamically designed for accuracy. The powder charge is 21.0 grains of SR4759 which will give you about 2,100 fps.

I shoot that in a stock factory stainless Ruger Gunsite Scout. That's my hunting load, but will do quite well on a target... at long range. It certainly beats the accuracy levels posted above by quite a bit.

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Bud Hyett posted this 18 January 2020

I know jacketed bullet cores are formed from extruded lead wire. In discussion with these bullet makers, they emphasize their determination to have uniformity in the wire. 

Note; When an object cools, it shrinks.

  • If a cylindrical object cools, this draws the circumference smaller.
  • If a rectangular object cools, this draws the dimensions smaller.
  • If either shape has a hole through the center, is heated and cools, the hole dimension becomes smaller as the object is heated by cause of expansion and becomes larger by the cause of cooling. 

Question: What happens within the interior of the bullet as it cools? 

  • Is there a migration of the alloy toward the external surface?
  • If there is a migration, is the center less dense and less uniform?
  • Will a center that is less dense and not uniform influence the path of the bullet? 
  • Can we casters even test this?   

I have run this through my mind several times and cannot think of a method to test this. Is the alloy in the bullet denser toward the surface and less dense in the center? Does this happen in a large enough factor to influence the bullet's path? Does not happen in a manner to enable testing?

There is a physical chemistry technique that can track the location of an element within an alloy, this is extremely costly. This technique was used by metallurgists in the 1970's to track element locations within an alloy in the quest to build better alloys used in defense and space. 

Wikipedia reference

With this concept in mind, I keep the casting alloy clean. I have often wondered if dropping bullets directly into cold water would freeze the alloy movement and bring greater uniformity. 

Your thoughts, are we chasing windmills? 

Farm boy from Illinois, living in the magical Pacific Northwest

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Tom Acheson posted this 18 January 2020

Might have to watch out for the credence we give to water dropping bullets. The hardness of each bullet will vary from other bullets handled a similar way during the session. Our cadence in opening the mold and lining up with the bucket will vary from bullet to bullet.  If we want all bullets in a session to have a chance of being close to the same hardness, heating ALL OF them up in the oven simultaneously and then move them ALL TOGETHER into a large container (sink next to the oven?) of cold water. The oven temp is around 10 degrees below the bullet slump temperature and the batch of bullets are often in the oven for about 45-minutes.

I’ve seen guys write that they store those bullets in the freezer to retard the bullet’s return to the non hardened state. 

Lots of theories on this!

How about a different variable.....the shooter and his skill, mindset, health, etc. the day of his range testing? Unlikely those factors are exactly the same on each range trip.

Tom

 

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RicinYakima posted this 26 February 2020

Somewhere about 2007 I wrote an article about different  brands and combinations of reloading dies. As I was measureing runout of case necks and bullets, less runout equaled smaller groups up to the point of chamber neck runout. On my best 1903 Springfield the runout is 0.003" from base of neck to top band of Lyman # 311284. I quit turning case necks since I bought Lapua and Norma brass. FWIW. p.s. I used linotype as long as I had it because I could make perfect bullets with less casting time. Now a softer mix of WW's and Monotype is working just as well, but reject rate has doubled to about 5%. Ric

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TRKakaCatWhisperer posted this 26 February 2020

For me it is obvious.  When I bring a guest to a match and he shoots a better score than I, with MY RIFLE, the potential for improvement is ME.

 

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Ken Campbell Iowa posted this 26 February 2020

as one who would like to see more playing with swaged bullets :

i observe that match 22rf bullets are swaged nearly perfect and shoot 1/2 moa

i observe that cheap 22rf bullets are swaged nearly perfect and shoot 4 moa .


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

i observe that this is confusing.  i do note that the front half of a 22 rf bullet doesn't fit in the rifling very snug. maybe a perfect bullet going in isn't so perfect going out of the barrel.

ken

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