BS- Weight segregating bullets in categories < .5 grain .5="">

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joeb33050 posted this 11 August 2018

 

Weight segregating bullets in categories < .5 grain

 

Weighing bullets to remove outliers makes sense, there are often strangers in the crowd. Segregating in classes < .5 grain never made a detectable difference in my groups. I’ve got weight data on > 10,000 cast bullets, available on request.

 

Threshold: Weigh bullets and melt the outliers. Divide the rest into < average and > average, shoot them. 

 

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Redleged posted this 11 August 2018

Hi Joe,

What do you consider to be "outliers?" I like to think more in terms of percentages than absolute grain weights. For example, a +/- 0.5 grain difference in a 50 gr - .224 bullet is +/- 1% of the target/average bullet weight, that same +/- 0.5 gr difference in a 200 gr - .310 bullet is now only +/- 0.25%, for a 405 gr .458 bullet, it's +/- 0.125%, and for a 500 gr bullet, it's a miniscule +/- 0.1%. I don't believe we even measure our powder charges to that level accuracy. As stated in your OP, there is probably little detectable difference in the accuracy/consistency caused by variation in bullet weights that fall within a certain deviation of the standard/average for the lot.

So, in terms of a percentages, where would you place those outlier "range markers?" Personally, for general shooting, I sort into three groups per batch of bullets cast with the same alloy at the same sitting using +/- 1.5% as my cull point. 

Low = < 1 - 1.5% of the average weight

Standard = +/- 1% of average weight

High = >1 - 1.5% of average weight (this is usually a very small portion of the batch)

Typically, I'll get more in the Low group than High group and those I use for practice and plinking (I cull and remelt those bullets outside +/- 1.5%.) I'm curious on your thoughts where you think the deviation from standard starts making a difference, and what your data may indicate. Thanks. Ed

Growing old is mandatory, growing up, however, is totally optional!

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Redleged posted this 11 August 2018

I'd like to add that I think the +/- 1% is fine for general rifle shooting out to 200 or 300 yards. Obviously, for match accuracy and/or long distance shooting, you would want to tighten the deviation to +/- 0.5%, or even +/- 0.25%. Even so, for a 500 grain - .458 bullet, 0.25% deviation is +/- 1.25 grains. That same deviation in powder weight for 70 grains of black powder is 0.175 grains. Ed

Growing old is mandatory, growing up, however, is totally optional!

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joeb33050 posted this 12 August 2018

For 26,948 bullets cast, the standard deviation average was .161 grains.

So, 65% were +/- .16 grains

95% were +/- .32 grains

99% were +/- .48 grains

So, if we weigh bullets, outliers are >.5 grains from average;

and if we segregate the plus and minus, each will be +/- .25 grains. 

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Larry Gibson posted this 12 August 2018

Weight sorting is necessary for extreme accuracy, especially at high RPM/velocity.  It is one of the methods used to select the most uniform bullets that are cast.  However, the method used most often for "weight sorting" (illustrated above) does not produce the best or any better results.  I have previously mentioned a method that does in other weight sorting threads.

However, if the accuracy criteria is <2 moa then the above method works fine.

LMG

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

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Geargnasher posted this 12 August 2018

Measure and weigh. Weighing alone won't catch all the bad ones.

Like Larry wrote, bullet defects matter a lot more at high velocity.

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Redleged posted this 12 August 2018

Larry,

Thanks for the response. I've read your weight sorting posts before on this and other forums, and then just re-read your post on the Goodsteel forum. What you say about sorting/keeping bullets at the higher end of the weight spectrum as "match grade" makes perfect sense, especially in regard to HV and high RPM. I'm still working to get good enough to keep all of my cast bullets within +/- 0.5 grains of average (especially the higher weight .45-70 bullets. I can't even fathom keeping +25K to that standard! Ed

Growing old is mandatory, growing up, however, is totally optional!

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John Alexander posted this 14 August 2018

I don't have any experience with CBs over 2,000 fps. or shooting them over 200 yards. But within those limits if the casting is at a uniform cadence and the mold and alloy are working well the bullets will probably vary less than 1%. I have never seen any proof (but plenty of opinions) that weight sorting such bullets improves accuracy even a little, no matter how reasonable it may sound. 

 

I stopped weighing bullets for matches over 25 years ago after shooting countless pairs of groups with one group consisting of carefully weigh sorted bullet and the other consisting of a mixture of the heaviest and lightest bullets in that lot. The bullets with the widest range of weight shot as well as the uniform weigh bullets. 

 

If you are already weighing bullets this is a very easy and quick experiment to do and I don't understand why everybody doesn't do it and find out the truth for themselves instead of listening to the learned opinions of others (who also haven't done the test).  If you disregard all the sage advice and shoot enough pairs of such groups you will probably find the same thing as I have. If you find that weighing bullets improves accuracy you should write an article for the Fouling Shot and shut up heretics like me.

 

A bit of theory - if a bullet is, say .5% lighter than average it should go a little faster and print a little higher than an average weight bullet. However, its BC will be a little lower because of its lightness which means that it will decelerate faster partially offsetting the higher speed. Additionally, if it gets out the muzzle a bit faster the recoil won’t have raised the muzzle as much as with a heavier bullet. this also counteracts the effect of the higher velocity, More deceleration and less muzzle rise both tend to counteract the faster muzzle velocity. However, all of these factors are TINY compared to the variations in chamber pressure from shot to shot of several thousand psi.  This large variation in chamber causes significant variations in muzzle velocity that complete dwarf any tiny variations in muzzle velocity that might be caused by less than one percent variation in bullet weight. So it is unreasonable to even expect that a 1% variation in bullet weight would affect accuracy.

John

 

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Larry Gibson posted this 14 August 2018

John

Even with velocities below 2000 fps weight sorting, if done correctly, can be of benefit. 

An accurate rifle, an accurate load, and an accurate shooter are all necessary to really see any difference.

If one is capable of your experience and expertise weight sorting may not be that necessary at lower velocities and dependent on the capability of the rifle involved.

If one does your test and ends up with the "bell curve" often described then you are correct; selecting bullets by "weight increments" will most often not show any benefit.

However, the classic "bell curve" of weight sorted bullets is telling us we are not really casting the best, most consistent bullets regardless of weight.  We should look at refining our alloy and/or casting technique.  A proper weight sort "curve" should rise quickly to a "plateau" and then drop off with very few bullets (as illustrated in previous threads on this topic).  The majority of the bullets cast should fall within the "plateau" (60 - 80%).  Those bullets should be well below the 1% variation.  For example my 158 gr 30 XCB bullets selected for match use by this method will be within .15 gr variation +/- of each other.  That is considerably less than 1% of 1.58 gr variation in weight. 

Even when weight sorting by this method 314299s I use the "plateau" bullets with a .25 gr +/- weight variation (1% would be close to 2 gr variation).  The difference in group size and score with my M39 in CBA military rifle matches where we shoot for score on target at 100 and 200 yards is very noticeable and predictable.  Casting and weight sorting with a classic "bell curve" never gave me the same results.

LMG 

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

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John Alexander posted this 15 August 2018


Larry wrote:

“Even with velocities below 2000 fps weight sorting, if done correctly, can be of benefit.”

Larry, I appreciate your comments and even agree with most of them. However, after firing hundreds of bullets in the simple test described in my last post I have been unable to show that weight sorted bullets shot a bit better than unsorted bullets under 2,000 fps and under 200 yards nor have I heard of anybody finding to the contrary.

=========

“An accurate rifle, an accurate load, and an accurate shooter are all necessary to really see any difference”

The majority of my tests were run with a combination that would barely fit in the worst end of Joe’s <1” category (a bit under 1” but not close to ½&rdquo . Because 1” and above would include 95% of the combinations our members are shooting my tests should be valid for all but the small group of shooters that can actually average under 1”.  As far as I know nobody in that class has bothered to run similar tests.

“If one is capable of your experience and expertise weight sorting may not be that necessary at lower velocities and dependent on the capability of the rifle involved.”

Anyone capable of steady casting with a mold, alloy, and temperature that is producing eyeballed “perfect” bullets will have bullets that are ALL well within about .25 percent of the average weight. My testing has repeatedly shown that bullets that uniform can’t be improved by sorting and I have never seen evidence to the contrary.

I have carefully read and understand your approach to weight sorting bullets. Well cast bullets may not always fit a symmetrical bell-shaped curve, but I think you are making a simple problem more complicated than it needs to be and sorting bullets to a level of precision that is unneeded (for CBA match type shooting.)

 “For example my 158 gr 30 XCB bullets selected for match use by this method will be within .15 gr variation +/- of each other.  That is considerably less than 1% of 1.58 gr variation in weight.” 

Even when weight sorting by this method 314299s I use the "plateau" bullets with a .25 gr +/- weight variation”

This amounts to bullets that vary only .0009+/- from the average weight (not unusual for well-cast bullets).  These bullets are coupled with a system where chamber pressure, human capability, and conditions vary far more from shot to shot making such extreme uniformity in bullet weight unneeded and its contribution to accuracy insignificant.  That is why no one has shown that well cast bullets can be improved by weight sorting to .1 grain or even .5 grain in head to head tests of sorted vs. unsorted bullets of good quality.

John

 

 

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Larry Gibson posted this 16 August 2018

That is why no one has shown that well cast bullets can be improved by weight sorting to .1 grain or even .5 grain in head to head tests of sorted vs. unsorted bullets of good quality.

John

 

That is where we disagree, it has been proven. 

I have proven it both with heavy match rifles and with milsurp rifles.  Others have also.

It is why I no longer weight sort the old way expecting a classic bell curve.  It's also why I refined my casting technique and alloy where the weighed cast bullets no longer give a "bell curve". I expect the "curve' to now plateau out at the heavy end.  The bullets used in that "plateau" have proven to give the best accuracy at both medium (1700 - 2000 fps) and at higher velocities (2000 - 3000 fps).  I have posted the results in other threads on this forum.

 Not arguing with you or your results as perhaps you cast bullets sufficiently well as you've a lot of experience and your bullets would all fall within the plateau of that sort method anyway.  However, many don't cast that well and because weight sorting doesn't apply to you doesn't mean it won't apply to or be useful to them.  Using the proper weight sorting technique can be a measurement of the quality of cast bullets the caster is producing with his alloy.  It could be the means to learn to cast better bullets because how does one know/measure that their bullets are "well cast bullets"

We both know many casters think their bullets "look good" but how are other less experienced casters to know they are?.  Proper weight sorting after visual inspection will tell them. 

LMG  

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

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John Alexander posted this 16 August 2018

Larry,

Well we agree on something. I'm sure it is possible to cast bullets badly enough that weight sorting would help.

I will try to find the thread where you proved that weight sorting helped I guess I missed it.

John

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OU812 posted this 16 August 2018

I weigh to check for odd ball bullet weight. Sometimes the mould will not close good and cause heavier bullet weight...diameter will be larger also.

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frnkeore posted this 16 August 2018

The only problem with suggestions that people run this test or any test like it is that for the most part we all come to the table with preconceived notions and egos so unless its a totally blind test where the shooter doesn't know which batch of bullets they're shooting they'll get, or imagine, the results they expect. I'm also not too sure all the testing being described and data being produced means much anyway unless its done with super accurate guns in a Houston Warehouse type environment.
-------------------------------------------------------------------------------------------------------------------

This is the area that really matters, in testing, relatively small improvements, such as the .5 gr difference, in a visually perfect, 200 gr bullet.

Cast bullets, are still a unsolved mystery and testing needs to be done carefully (at least one blind test) and then redone by someone else (at least one other person) to have any real credibility.

Frank

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John Alexander posted this 16 August 2018

I agree with Pat that human nature will ruin our testing if we are not totally disciplined and completely honest. We all have a result we would like to see or at least expect to see and it is hard to avoid bias.  The answer is blind testing The good news is that blind testing isn't hard.

I disagree that you must have perfect equipment and the Huston warehouse to get useful results, but I have already made my arguments on that issue  in this thread and others.

I also agree with Frank that the work should also be redone by somebody else, but not sure how you achieve that.  I have published in TFS the results of some of my testing, several that produced results counter to the conventional wisdom. At first I thought someone would be irritated enough to repeat the test to refute my results, since it was clear that CB shooters don't like to be told that some of their time honored and time consuming procedures don't improve accuracy.  I got plenty of opinions that my findings were wrong, some hostility that sacred cows were being questioned, but mostly nothing.  In total, over several articles and several years I only know of two shooters who have run similar but different tests and discussed their results on our forum.  

Unless things change, my prediction is that we will see the same  improvement in CB accuracy over the next 20 years as the last 20 -- none.

John 

 

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pat i. posted this 16 August 2018

I agree with Pat that human nature will ruin our testing if we are not totally disciplined and completely honest.

And therein lies the rub.

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Ed Harris posted this 16 August 2018

With proper casting technique, producing well filled-out bullets with good bases and no visual defects, weighing isn't necessary.

John Ardito never weighed a bullet, but he WAS very fussy about his casting technique, bullet fit and visual inspection.

Most detrimental to accuracy are small shrinkage cavities which occur as the metal solidifies.  Pouring a large sprue to keep the gate flow liquid as long as possible, and providing adequate time for the sprue to harden before opening the mold, such as alternating between to molds to maintain a uniform casting rhythm, are most important.

But I agree with Larry, if shooting a common hunting or military rifle which even on its best days does not average m.o.a. over a series of groups, weighing bullets is a waste of time.

Competition benchrest shooting with accurate rifles capable of sub 3/4 m.o.a. grouping with good ammo on demand, anytime anywhere, THAT is a different breed of cat.

Using gang molds, not sorting by cavity, using ordinary care in casting and visual inspection I expect 2 inch ten-shot groups at 50 yards with .38 Special or .45 ACP wadcutter ammunition assembled on a Star progressive machine, firing off a Ransom rest with good PPC revolver or accurized wadcutter gun.  An iron-sighted cowboy or Bunny Gun with correct chamber shot off sandbags should approximate this.

Applying the same standard to .30-'06 plainbased gallery loads fired in common iron-sighted bolt action hunting or military rifles I would expect 2-1/2" groups with open iron sights and about 2 moa with peep sights, or 1-1/2 moa with a common hunting telescope not exceeding 4X.  Simple reality here. 

 

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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Eutectic posted this 17 August 2018

Casting does not produce a bell shaped curve. There are limited reasons to produce an overweight bullet and these are easy to see measure and correct. There is more latitude for underweight bullets, and the big one is voids or shrinkage cavities in the bullet.

With short bullets like 38 and 45 pistol bullets my experience is the same as Ed's. Voids are very rare and with careful casting and visual inspection the bullets are good enough for match shooting.  I stopped weighing pistol bullets.

With some bullets voids are a small problem and some cannot be seen on visual inspection. With 220 grain 30 caliber bullets , one in several hundred, was light. Long heavy bullets like 500 grain 45's can get shrinkage voids. Some I could see in the cut off sprue some not. I used to weigh all these. Maybe my casting was not perfect.

Steve   

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joeb33050 posted this 17 August 2018

Casting does not produce a bell shaped curve.

My casting and weighing of >29,000 bullets clearly showed that their weights formed "bell curves", sometimes with small standard deviations. . Average sd was .161 gr. Cast up a couple of hundred, weigh them and put them in order by weight. Maybe take a picture. Don't worry about the invisible voids, we can't see them.

 

There are limited reasons to produce an overweight bullet and these are easy to see measure and correct. There is more latitude for underweight bullets, and the big one is voids or shrinkage cavities in the bullet.

With short bullets like 38 and 45 pistol bullets my experience is the same as Ed's. Voids are very rare and with careful casting and visual inspection the bullets are good enough for match shooting.  I stopped weighing pistol bullets.

With some bullets voids are a small problem and some cannot be seen on visual inspection. With 220 grain 30 caliber bullets , one in several hundred, was light. Long heavy bullets like 500 grain 45's can get shrinkage voids. Some I could see in the cut off sprue some not. I used to weigh all these. Maybe my casting was not perfect.

Steve   

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Larry Gibson posted this 18 August 2018

A few months back I posted this on a couple forums, don't remember if here or not.  At 600 yards with the 30 XCB at 2900 fps I shot 4 groups (46 shots total) that averaged 1.3 moa.  The smallest group (11 shots) went into 5.9" or less than moa......again with a 2900 fps load at 600 yards.  Point is you're not going to do this with unweight sorted (correctly cast and sort method) bullets.

 

LMG

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

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