To 'Weigh' or 'Not to Weigh'

  • 12K Views
  • Last Post 26 November 2009
CB posted this 04 May 2007

Quotes from 'Bullet Moulds' topic:

Veral Smith wrote:  --  May I suggest to anyone who weight sorts.  Try shooting everything that falls from your mould and looks good, and compare accuracy to your most carefully weigh sorted lots.  You probably will never weigh sort again. John Alexander wrote: Not that Veral needs any support for his ideas on casting from me, but I have run the test he suggests several times shooting alternative groups of bullets from the same lot. One group with uniform weights, one group with both the heavy and light mixed, one with mine run and so on.

I have NEVER been able to see that shooting bullets sorted by weight helped a bit and it often looked like the mine run bullets did a bit better but I have never done statistical analysis on the numbers to see if the difference was significant.

Of course all my tests were on 22 caliber bullets. You thirty caliber types will have to run your own experiments or just take Veral's word for it.

John

Weighing CBs is something I can do for control over quality.  I would find not doing it isn't really something to brag about.  Weighing bullets will tell you that there is not as much lead in one bullet over another.  Is it shrinkage discrepancies?  Is it a hollow pocket somewhere inside the confines of the surface of the cb?  Who knows?  I doubt that there is any difference between .2 grains or even .4 grains in bullets, but I'll find a few .5 to 1 grain drop in 214 grain CBs in a casting session of bullets that to me is definitely wrong.

Assuming these 1 grain differences in bullets is a hollow pocket somewhere under the surface of a bullet, it can have drastic affects on accuracy from my point of view, without facts to prove it because there is no way to find an internal void without destroying the bullet for testing.  If the void is near the center of mass and/or rotation, then rotational stability is not affected as much as a void just under the surface on the outer diameter of center causing more of an outa balance force in a 1-10” twist speeding bullet at 2,000fps. A 30 caliber bullet over a 22 caliber has about a 28% difference in diameter, 14% in circumference. Diameter forces are greater than ratio to ratio differences between the two bores.  That is enough difference for concern for me. So John, that is one advantage you have with yer 22s.................Dan

Attached Files

Order By: Standard | Newest | Votes
PETE posted this 05 May 2007

Here's my take on it.

I've weighed bullets almost as long as I've been shooting cast bullets. Both round and cylindrical. Mostly this is done to segregate them out into .1 gr. lots so that no group will be shot with a bullet that has more than half a gr. + or -, and to find that odd bullet that weighs more or less than the norm I set for each lot. I've always noticed something peculiar when shooting those carefully weighed and inspected bullets. They don't seem to shoot any better than the “rejects” I use as foulers.

When working up loads I'll shoot a round or two into a fouler target for each load I'm working with, and then swing over to the record target. Invariably when done with that set of experiments for the day the group on the fouler target is as good or better than the one the carefully selected bullets make. This has always puzzled me since the fouler “group” will also consist of about four different powder charges to.

I've always thought this was one of those flukes that happen regularly, like getting a 1/4” group out of a gun that normally doesn't do better than 1".

With Veral & John's comments I think I'll be doing some experiments along those lines this Summer.

PETE

Attached Files

rk4570 posted this 05 May 2007

I am reading this line as a “Lurker” who has no exp. in CB matches. I do cast & shoot a lot of BP bullets in 38 & 45cal. I do weigh all of my bullets (365gr in 38 & 550gr in 45)but the only difference that I can find is confidence in the loads,& they sure LOOK nice on the bench before loading!!

Attached Files

CB posted this 05 May 2007

Pete,

I will be interested in the result of your testing. I may do some more myself. It is something that should be pulled together and written up for the Fouling Shot since a lot of people do a lot of weighing and if it isn't doing any good, or maybe even doing some harm as Veral suggests we ought to know about it.

Of course even if it doesn't do any good there is no reason to stop doing it if it makes you feel better and they do look nice lined up as RK4570 noted. This is after all a hobby and we don't have to turn a profit at it.

On caveat on the testing I mentioned. I do have records on dozens of alternating groups that fail to show any improvement from weighing but they are almost all in the 0.8 to 1.2 MOA level. At a higher level of precision, as Dan achieves with disgusting regularity, the answer could be different.

Weighing or not weighing is not a matter to brag about. It's just that we ought to try to find out if it helps. Dan's theory seems reasonable and I certainly weighed a lot of bullets before I tested on the basis that it seemed like a reasonable thing to do but after not finding any difference I gave it up.

John

Attached Files

CB posted this 05 May 2007

I weight sort because in my eyes it's the thing to do but to be honest I could never tell any difference in accuracy between weighed and  unweighed bullets on the target. I always used the unweighed bullets for foulers and sighters and plenty of times to finish a match or group when I ran out of “match quality” bullets, goofy but it's what I've done. I think for the most part Veral and John have it right.

Now for a question pertaining  to air pockets. Has anyone actually ever found definitive proof that there was a void in a light bullet? I know people always talk about it but has anyone ever dissected a light bullet and seen one in person. It would seem to me that it'd take an extreme circumstance to cast a bullet with an air pocket in it using normal techniques for casting good bullets, alloy and mould up to temp. and such. I realize bullets will vary in weight during a casting session but I'm not at all convinced air has anything to do with it.

Pat  

Attached Files

PETE posted this 05 May 2007

 John,

  Here's another idea to ponder on. Some of the Schuetzen shooters will shoot their bullets strictly in the order cast without weighing. Still others will weigh them, throw out the light or heavy ones, and shoot them in the order cast.

  Some of the reasoning has to do with the wgt. variation you get as you cast up a lot. In this regard I've noticed that bullets tend to weigh more toward the end of a session.... on average.

  Then we have the people who weigh their primers! :)

 Pat i.,

  On air pockets...... As has been mentioned there's no way short of destruction to test for this. Quite a few years back on the old BP-L I had quite an argument with a guy who said that most, if not all, bullets had a void in them. If I didn't believe him I should cut a few dozen apart and see!  I argued that this might be the case in bullets that weighed to much outside a norm for the lot. For arguments sake say 1 gr. under.

  It's been my understanding that when you pour a bullet the metall freezes from the bottom to the top, and from the sides to the middle. Makes sense if you think about it. If this is the actual case then any voids should be along the center line, and toward the nose or base depending on the mould. In that case then the rotation of the bullet should reduce the effect on the bullets flight.

  But if there is an air space, how does the air get in there? I cast with a ladle and always keep pressure on the sprue hole, and leave a good puddle for the bullet to draw on if needed. My puddles seldom have a dimple in when they harden. To me this indicates that there is no “suck in” as the bullet harden.

  There is one type bullet that has me confused. The one's that weigh a gr. or better above the average. I might have 200 bullets that weigh within .2 or .3 of each other but there always seems to be one or two that will weigh a full gr. heavy. I can't even begin to guess why.

PETE

Attached Files

jimborton.no.one posted this 05 May 2007

I thank You can get difference in weight by not holding the mould tight togather when you are pouring bullets! they can be bigger around but to small to be able to measure!  Don`t take much to get a 1 gr increase!

Attached Files

CB posted this 05 May 2007

PETE wrote:  Pat i.,   On air pockets...... As has been mentioned there's no way short of destruction to test for this. Quite a few years back on the old BP-L I had quite an argument with a guy who said that most, if not all, bullets had a void in them. If I didn't believe him I should cut a few dozen apart and see!  I argued that this might be the case in bullets that weighed to much outside a norm for the lot. For arguments sake say 1 gr. under.

 

Pete,

Since the bullets in question are rejects in the first place destructive testing shouldn't be an issue, but since we're talking about lead bullets here destroying a few hundred good ones shouldn't be much of an issue either. I believe theory turns to fact over time because folks with the loudest voices who speak in absolutes are the ones people tend to listen to even if there's no proof that what they're saying is true or they know what they're talking about. Did you ask your antagonist on the BP-L forum if he ever dissected a bullet like he suggested you do to prove he was right? 

Getting back to the topic, I'll continue to weigh match bullets because it's what I do and isn't too much of a bother with electronic scales but for all intent and purposes it probably isn't necessary. I never bothered weighing for pistol or casual shooting and won't start now.  

Pat 

Attached Files

CB posted this 06 May 2007

Bob Birmley had and excellent article in the Fouling Shot a couple of years back telling about finding cavities just below the bullet surface by tumbling and tests to show that by sorting these out accuracy improved. Great article with pictures of the voids as I remember.

Of course this isn't quite what is being discussed but is somewhat related.

John

Attached Files

PETE posted this 06 May 2007

 Jim,

  I will agree that a 1 gr. difference is easily possible in a casting run. What I'd like to know from your experience is what do you consider an acceptable wgt. range in your .32 MS. I believe you shoot a bullet of about 200 grs. I know you and Barry have done a lot of experimenting at Barry's range, in connection with your mould business, and am wondering if you'd looked into something along this line.

 Pat i.,

  Yes! The fella I was arguing with said he'd dissected a lot of bullets and found everyone had a void in it.

  But, I always felt/feel that a lot depends on how someone does something. If you have a poor casting technique then you will probably have voids. The reverse is true to.

  I know there are not many that will believe this, but casting 500 + gr. bullets I can cast within + or - .2 gr. for a lot of 200 bullets. For .30 cal., and under, I can cast within + or - 1/2 a gr. for a lot of 400 bullets with 85% right on the nose. Out of these I will have possibly a 1/2 doz. I consider rejects and use for foulers. I've been accused to my face that this is not possible. Of course it isn't...... if you can't do it. But I know at least one other shooter who can to so it's not impossible.

  So I look at the void question as why should I ruin even the rejects, by cutting them up, since I'll use them for foulers. If the argument is true and every bullet does have voids all you can do is weigh the bullets out so as to determine which might have voids big enuf to possibly cause accuracy problems. The same would hold true if the idea is false. Weighing the bullets would show those that MIGHT have a void in them.

  But, lets say all my bullets do have voids. With my wgt. limits they would have to be pretty small. Since I firmly believe that all voids will be on, or close to the centerline how much will they affect accuracy? What would be the purpose, other than proving a theory, of cutting bullets up?

  Rather than argue the void question I think a better subject is to determine how much wgt. difference you can have, for a given caliber, before it does affect accuracy. Some BP Shilouette shooters feel a 5 gr. difference in a lot of 525 gr. bullets is more than acceptable. Most Schuetzen shooters seem to feel a + or - 1 gr. doesn't hurt a thing.

  I'll agree with you that sometimes the loudest voice carries the most wgt. in an argument. As does someone who is considered an expert on the subject. It's funny tho. What I've found out is that the more I learn the more I find out I don't really know a lot at all.

  On weighing...... I'm with you. Actually I weigh ALL my bullets since if I'm not shooting a match I'm doing some type of experiment so I want to eliminate any source of error that I can.

 John,

  No! I think comment  is appropriate to the discussion. If that article holds true for all cast bullets then my idea of the voids being centrally located in a bullet would be wrong. The guy I was arguing with on BP-L said all the voids he came across were toward the center line if IIRC. Been 10 years or better since we had the “discussion".

PETE

Attached Files

jimborton.no.one posted this 06 May 2007

Pete Im with you on moulding good bullets! All my bullets are the same weight with in + or - .2gr. most weight the same! I weight as I cast anything off more then that go back in the pot! Dont want any rejects at my bench! If you mould right there will be no void in your bullets! The .2gr =or- could be the scales!

Attached Files

CB posted this 06 May 2007

John Alexander wrote: Bob Birmley had and excellent article in the Fouling Shot a couple of years back telling about finding cavities just below the bullet surface by tumbling and tests to show that by sorting these out accuracy improved. Great article with pictures of the voids as I remember.

Of course this isn't quite what is being discussed but is somewhat related.

John

This is exactly what I was discussing under my reply. That is how I started finding voids or air pockets under the surface of my bullets! I guess I should of gave Bob credit for what I was discussing. Bob's fine article in F/S #163-13 caught my attention a year ago, along with knowing Bill Anderson and Mitch Migliaccio who also tumble bullets. A follow up article in F/S #167-20 by Phillip G. Kaster confirmed what Bob was talking about. Of course the articles were not conducted under systematic scientific criteria, so it is probably more wives's tales than facts.

I started tumbling bullets a year ago to prove this for myself and found the voids in my bullets, even ones that weigh the same! I never did an accuracy test, but used the defected bullets for 2nds, but see they most often times shoot really good barn-yard accuracy on my sighter target groups at 1.2". For me the casting pot serves two purposes, one to cast bullets out of lead and one to re-make bad bullets into good ones. Why I cast bad ones sometimes I don't know, but it's probably because of my imperfect unscientific casting techniques....................Dan

 

Attached Files

billwnr posted this 06 May 2007

I'd bet that most of the shooters who win their classes weigh their bullets.

In my opinion the plain base shooters who shot their bullets in order of being cast were doing the equivalent of weighing their bullets.

Attached Files

PETE posted this 06 May 2007

billwnr,

I never liked the idea of shooting bullets in the order cast. An experiment I carried out many years ago, where I weighed the bullets and kept them in the order cast, showed that those “odd” ones could show up at any time. Either light or heavy.

I've also done the above and couldn't find a difference in accuracy than doing it my normal way of separating the weighed bullets out in .1 gr. increments so that no possible group, or score, would be shot with any bullet weighing more than a .1 gr. from all others.

Altho I use some of the rejects for foulers when experimenting during a match I do like Jim does and only use the best bullets I can make, even for the foulers, as I want to know what the gun/load is doing under the current conditions before I go for record.

As Dan points out...... Works in my world!

Attached Files

TomG posted this 06 May 2007

One sure fire way to get heavy and light bullets in the casting session is to let the mould and/or the pot temp vary. I have a temperature meter that is driven by a thermocouple. I once made a threaded hole in a mould and attached the thermocouple to it with a screw. I monitored mould temp. and weighed each bullet as it was cast. Sure enough, the weight followed the temp of the mould. As the mould heated up, the bullets became heavier. Much more than a grain if I remember correctly. Thus, if you start out with a mould not quite up to temp. it will cast light. That is not to say that these are bad bullets as they aren't.

I also noted in my test that when I had an interruption in the casting cadence, I had lighter bullets as the mould cooled off. Also, when I threw a cold ingot or two into the pot, the alloy temp went down and so did bullet weight. Somebody else mentioned not closing the blocks tightly. This will cause heavy bullets. Also, if the sprue plate rides up and doesn't lay flat on the top of the blocks you will get a longer bullet and the bullet will weigh more than usual. It will also have a slightly out of square base if this happens.

Light bullets are a different story. If they fall way out of the normal distribution, I throw them back in. I usually cast batches that run from 1 to 1 1/2 grains from the lightest to the heaviest. If they fall out of that on the light side, they obviously have some internal void that made the light in my estimation. It's always easy to re cast them and chances are they will be good the next time around.

I always sorted my bullets by weighing and placing them into lines of equal weight. The bullets, if you had a hundred to two hundred, usually formed a nice bell shape curve that gave me an indication of the quality of my technique during that casting session. Simetimes, they would be skewed to one side but most, when laid out, formed a normal bell curve shape.

I packaged them into boxes starting from the heaviest row and worked toward the light end. That way, most bullets were very close to each other as I loaded them out of the boxes and shot them.

I must confess that the ones from the light end seemed to group just as good as the heavier ones. But again, I threw the ones that were out in left field back in the pot to be re cast. I often found one bad casting out of a hundred or so. I called that one “the bullet from hell". Weighing found this bad one as it would usually pass a strick visual inspection but be light. Since weighing bullets makes me feel better, I do it.

Tom Gray

Attached Files

CB posted this 07 May 2007

I weigh (almost) every bullet I cast, and have done so for many years.

For not quite as long a time I've recorded data about the bullets cast and saved these records.

To prepare for this answer I cast Borton-Darr 185 grain 30 caliber bullets yesterday, 5/6/07.

Total bullets cast were 124. All were inspected under a 4X magnifier, 7 rejected for visual flaws. The rest were weighed.

Grains  Qty.

183.3   4

183.4   12

183.5   48

183.6   16

183.7   7

183.8   8

183.9   5

184.0   6

184.1

184.2   1

184.3   4

184.4   1

184.5   1

184.6

184.7.

184.8   1

184.9

185.0   1

 

186.0   1

 

186.2   1

Inspecting and weighing this lot took 54 minutes.

Now this is an unusual result, but it serves to illustrate the benefits of weighing after casting.

A. Weighing allows you to eliminate “strangers". My average lot size over the 14620 cast bullets recorded is 107. This does not include the “strangers", those bullets that weigh more than a half a grain away from the mean. I generally find 1-3 of these. Yesterday there were many, all those heavy bullets that passed the visual inspection but weighed a lot more than the average. I suspect that a piece of lead got on one of the mold halves for a while, causing the heavy weights. I think I can see and feel a thicker-higher parting line on those heavies.

B. Weighing allows you to segregate or class bullets. From 183.3 to 184.0 there were 106 “good” bullets. I shoot sets of 25 shots, every set is an experiment. I need sets of 25 bullets plus 1-2 in case I drop one. From 183.4 to 183.6 are 76 bullets, that weigh close to the same. Then the 26 from 183.7-184.0 are another lot of ~25. And the 4 weighing 183.3 are marked as foulers.

C. Weighing allows you to understand better what is going on during casting. I had suspected trouble with a lot of 25:1 that I bought, and had been casting with a mixture of lead and a little foundry type. After each lot I added lead to the pot, wanting softer bullets. Each lot had the average weight increase. This lot has an average of 183.6 grains, and a standard deviation of .171 grains.(183.3-184.0 only.) There's not enough ?tin?, certainly not enough something, because the quality of the bullets has gone down based on the variation and the appearance. There are many other lessons I've learned by weighing bullets.

D. Weighing allowed me to calculate and record the average weight and standard deviation of weight of each lot of bullets cast; and this data leads me to this conclusion: After eliminating “strangers", the standard deviation of bullet weights, on average, for >14000 bullets, is .151 grains-and this includes some very messy results. Then it is reasonable to say that under proper conditions a caster should be able to cast bullets that weigh +/-.5 grains virtually every time, and with culling, lots of bullets can be held to +/- .3 grains easily. ( I suspect that variation is not a function of average bullet weight, but don't know, yet.)

The EXCEL program for calculating average and standard deviation of bullet weights, and recording the results, is in the book, appendix, in FILES, at http://sports.groups.yahoo.com/group/CB-BOOK/files/

"Bullet Weight Calculator and Record."

 

Then there is the associated question: “Do variations in bullet weight affect accuracy?

I can provide some data on that, tomorrow.

joe brennan     

Attached Files

CB posted this 07 May 2007

John Alexander wrote: Bob Birmley had and excellent article in the Fouling Shot a couple of years back telling about finding cavities just below the bullet surface by tumbling and tests to show that by sorting these out accuracy improved. Great article with pictures of the voids as I remember.

Of course this isn't quite what is being discussed but is somewhat related.

John

When this article appeared in the FS I tested three batches of 100 bullets, two from LBT moulds and one from a Mos, to see if I could replicate Bob's results and couldn't. Maybe it's the quality of the moulds I was using, maybe it was because I ladle cast and usually run the alloy pretty hot, or maybe it was dumb luck but no matter I didn't find any air pockets under the skin that tumbling revealed.

Am I going to continue to weigh bullets? Yes. Do I think bullets having a half grain difference in weight are going to effect my targets as much as a five mile an hour wind shift? No. 

Pat

Attached Files

fa38 posted this 07 May 2007

<<<I started tumbling bullets a year ago to prove this for myself and found the voids in my bullets, even ones that weigh the same! I never did an accuracy test, but used the defected bullets for 2nds, but see they most often times shoot really good barn-yard accuracy on my sighter target groups at 1.2". For me the casting pot serves two purposes, one to cast bullets out of lead and one to re-make bad bullets into good ones. Why I cast bad ones sometimes I don't know, but it's probably because of my imperfect unscientific casting techniques....................Dan>>>

When I tumbuled bullets to moly coat them the surface voids would show up as shiny indentation on the bullet surface.  I would shoot them for offhand practice at 100 yards instead of 200 yards figuring they could not go to far off the aim point.  If a shot was way off call I would just discount it.

This is off point but another thing tumbling does is put a small ring of increased diameter just north of the bullet base. 

fa38

Attached Files

CB posted this 08 May 2007

Interesting discussion. It's always interesting to hear what people are doing.

To avoid any misunderstanding let me say that if you like to weigh bullets or it gives you confidence that's your business. It's a free country and CBs are a hobby. So I am not criticising when I make the remarks below.

Several reported that they always weighed or kept bullets in order and what their tolerances were but none reported on tests to show that it improved performance. If somebody has done such tests it would be nice to hear about it. Joe has promised us some data on that question. So I have hope. I would like to know if the results of my tests that show it is a waste of time can be replicated. I would be just as happy for more comprehensive test to refute my finding. Maybe the sample was too small or something.

It is reasonable to assume that it may help but then “common sense” would also tell you that a lead ball falls faster a lot faster than a wooden ball, that the sun rotates around the earth or that the earth is flat if you don't go further to find out.

The fact that the winners of the matches all seem to weigh doesn't prove much since almost all competitive shooter weigh so naturally the winners weigh. The question is - does weighing improve accuracy.

I thought Veral's provocative claim that it may hurt would have generated more interest.

Again, if you like to weigh, you won't get any criticism from me, but I have never see the results of a serious effort to find our if it helps.

John

Attached Files

sundog posted this 08 May 2007

I really don't care one way of the other if anyone else weighs bullets. I weigh match bullets. About eight or nine years ago I started the military bolt matches at my club. I've always shot cast in these matches. About four or five years ago I got my first digital scale which made bullet weighing fast and easy. I started weighing match bullets into very small lots of .1 or .5 grains. That was too tediuous. Then, I discovered that +/- 1% of average weight was just as good (maybe not for BR but okay for mil bolt), that is +/- 1 grain of average for a 200 grainer. Any of us can LOOK at a bullet and decide whether we want to shoot it or cull. If it looks good, what you cannot tell if it is way outside the norm by weight unless it goes across the scale. The ones I'm primarily concerned with are the light weights. Those are either culled or go for barrels warmers. I've reduced flyers to virtually zero. Now if a round goes out of a group, it's on me, fail to read the wind, crappy trigger control, whatever. No more wondering why. I've never cut open a light weight looking for voids, don't intend too.

Attached Files

CB posted this 08 May 2007

"Do variations in bullet weight affect accuracy?

This is probably the wrong question.

The weight of a given bullet can change with:

a change in the alloy

a hole in the bullet, not visible to the inspector

a visible hole or defect in the bullet

Maybe the question is:” In bullets with no visible flaws, cast of a constant alloy, what is the relationship between weight variation and accuracy?"

I don't know how to make a lot of bullets that are cast of the same alloy, have no visible flaws, and vary in weight. I can and do make some every time I cast, but I can't make, say, 27, for testing purposes.

In the book, at http://sports.groups.yahoo.com/group/CB-BOOK/files/ , “3.5 Damaged Bullets” shows the results of testing purposely damaged bullets for accuracy.

Here are tests of bullets with 45 degree flats filed in the base band, certainly removing some material = weight from one side.

At the end of these tests I was left with two surprising results.

Bullets with damaged bases are not wildly inaccurate-they don't hit a foot away from the good bullets at 100 yards.

Bullets with damaged bases are not reliably inaccurate. I would expect that a defective = different in weight or shape bullet would hit over there or over there or someplace other than where perfect bullets hit. I would expect a doughnut-shaped group fired with defective bullets. Instead, the groups fired with 64 each good and filed-base bullets both show a central tendency; there are many filed-base bullets that hit close to center.(Picture attached, I hope.)

Means that “defective bullets tend  to hit outside the group center", not “defective bullets do hit outside the group center."

So, to test, I think we must use bullets with visible defects purposely introduced to simulate bullets with not-visible internal “holes".

How much should the weight vary for the experiment?

If we assume that bullets weighing more than .5 grain from the mean should be re-cycled, that lots of bullets can be controlled to weigh +/- .5 grains, then I'd suspect that we'd want to know what a +/- .5 grain weight variation has on accuracy.

In the appendix of the book there's the EXCEL workbook “Bullet Hole Weight” that shows weight in grains of  holes (spheres) of different diameters. Also calculates weight of a hole of any diameter you choose. A one grain lead sphere or hole is ~.044” in radius or ~.088” in diameter. This seems a big hole to be in even a 30 caliber bullet, much less a 22 caliber.

However, if we could learn something about 1 grain weight variations and accuracy, maybe we'd know what steps to take next.

More tomorrow.

joe brennan

 

 

Attached Files

Show More Posts
Close