Will Sorting by Bullet Weight Improve Accuracy

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Wm Cook posted this 03 July 2022

A diversion from the thread "Mold Temperature".

The topic "Mold Temperature" on a different thread gravitated towards a good conversation that kicked around the pro and cons of sorting bullets by weight for the purpose of improved accuracy.  John's post suggested a separate thread to discuss sorting versus not sorting.  Since I had started the OP on mold temperature I thought it would be OK to start this new one.

(John Alexander wrote) Great idea for another thread. It would be nice if all the posters above who believe minimum bullet weight variation is important for good accuracy would all shoot a similar test.  It would be interesting to see the results.

 

(John Alexander continued) Sort of a cooperative joint experiment. I would be happy to participate if there is any interest.  Pretty easy to do even if two ten shot groups of each condition.

There are people with enough credibility on both sides of the "weigh or don't weigh" topic that it might be fun to work with.  Bud, Gunarea, John, Aaron and many others have decades of experience chasing small groups. 

I'm all in on this.  To get started I would like to suggest that someone take the lead.  Someone who has a track record conducting trials and writing articles that takes controversial subjects and wrings them out to see if the variable can effect change and take the lead.

Rather than beat around the bush I would like to suggest that Jone takes the point.  I recommend that John and another CBA member collaborate on a set of easy to replicate methods that maybe 4 others can follow close enough to make the test valid.  Since I started this thread I'd like to be the first to jump in with my "wish list" for Methods.

  • Use the CBA Group targets.  It gives the user a sighter target and a target for score for each of the variables (assuming we follow the suggestion of shooting x number of 10 shot groups.  X is defined as he number of variables being tested.
  • Consider limiting it to one cartridge so if you're talking about +/- .5 grain all results will be close to relative.  30 cal is the most caliber shot in the Nationals.  
  • Outline the expected bullet weight variation in tenths of a grain (drop or lubed) to be tested. 
  • Set a time limit on returns.  30 days is plenty.

If everybody jumped in with their wishes and wants like I just did this could turn into an endless mud wrestling match.  That's why I suggested a couple of the respected members of the group draft the methods and they'll be savvy enough to keep it simple. 

Volunteers could be sought on line or drafted off line.  I don't have a row to hoe in this, I just would like to see a structured test that will give me an edge.  I could do it on my own but if we have a small group kick it it may carry more respectability.  Sorry for being long winded.  Thanks, Bill Cook

 

 

 

 

 

My addiction to gambling starts and ends with me spending $ to try a powder I’ve never shot before.

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Wm Cook posted this 03 July 2022

It's possible that those that hold opinions regarding the value of sorting cast bullets by weight will or will not improve accuracy has been away from the forum.  Or maybe some would prefer to keep talking the talk instead of walking the walk. The reason for the latter could be for any number of reasons but I'm certain that no amount of communication on a forum will sway folks away from either position.

What was proposed is not difficult.  Someone write up a set of methods.  I recommend the participants use CBA groups targets.  We could use five targets with each having one bull for sighters/zero and one for record.  And I'm still pushing for similar calibers so the +/- weight variation is somewhat relative.

Allow one target to zero, shoot your pet load for record and to warm up.  The final four targets are each shot with 10 shot groups plus whatever you need on the sighter.  Sorting to the degree the methods allow two groups will be shot using weight sorted to .x grains and two groups will be shot sorted to .y grains. 

Your rifle does not have to be a bug hole producer.   If the rig normally shoots 2" with the best of the loads so be it.  You would be competing with yourself.

The only requirement is that the participants must be capable of using match grade casting, reloading and bench equipment and match grade casting, reloading and bench practices.  I hope I didn't hurt anyone's feelings and promise to drop the subject after this.  Thanks, Bill C.

My addiction to gambling starts and ends with me spending $ to try a powder I’ve never shot before.

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porthos posted this 03 July 2022

it might be eaiser to tune your casting technique to get the weights closer. i cast with a ladle and the weight variation is less that 0.2 (2 tenths of 1 grain).  i have a NOE 3 cavity mold for 303 that will hold that variation.

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Larry Gibson posted this 03 July 2022

I've been down this path before on this forum.  I have posted extensive test results. 

Here's the main problem (IMHO) with your discussion and test.  "Your rifle does not have to be a bug hole producer.   If the rig normally shoots 2" with the best of the loads so be it.  You would be competing with yourself."

To actually and realistically show the difference one must properly cast bullets of sufficient quality and one must weight sort them properly.   The usually reported "bell curve" weight assortment is not the proper method.  The curve must "flat line" at the heavy end for the majority of bullets.

One must use a rifle/scope/bench/rest combination that is accurate enough to tell the difference and one must be able to shoot accurately enough to show the difference.  One must also to honestly know the difference between a "called shot" and an actual "flyer".  Shooting a milsurp or commercial rifle with issue iron sights won't really show a difference.  Shooting at just 50 yards (which many do) won't show the difference.  Improperly weight sorting won't show the difference. And using a load with a large SD/ES ratio won't show the difference either.

I shoot a lot of unweighed cast bullets in my rifles when they are used for plinking, casual shooting or "blasting".  Almost all are GC'd and I just do a visual cull for defects when putting on the GC, sizing and lubing.  I am very happy with the results as most are when doing the same.  However, for serious accuracy for CBA competition and HV cast bullet use I weight sort.

Attempting to draw any conclusion based on comparison of okay accurate rifles to those capable of precision accuracy will not solve anything nor answer anything as it is apples to oranges comparison.  Not using a rifle/equipment of adequate accuracy capability to show the difference or having the ability to shoot accurately enough to show the difference also will be a problem.  

However, individually, such a test will more than likely just tell each tester whether his casting ability, shooting ability and rifle are capable of telling the difference with the load he is using whether weight sorting is beneficial to him.  

LMG

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

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Shopdog posted this 03 July 2022

I'm with porthos above....

Although bttm pouring,it is very rewarding being able to cast to extremely tight tolerances. To the point that,not only weighing becoming a waste of time but,it does move accuracy in a positive direction. The argument of shooting "culls" or anything other than preemo bullets,is also a waste of discussion. Don't cast poor bullets.

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RicinYakima posted this 03 July 2022

"However, individually, such a test will more than likely just tell each tester whether his casting ability, shooting ability and rifle are capable of telling the difference with the load he is using whether weight sorting is beneficial to him."

That is my position also, Larry.   

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Wm Cook posted this 03 July 2022

That's a very sobering thought.  In jacketed br there are few called fliers.  If a group opens up from the low .2's to the mid or high .2's its either the user, the load or the wind. With enough time on a stool shooting custom rigs the user rarely makes self inflicted mistakes.  By far, wind is the single greatest obstacle.  I got out shot all the time but it wasn't because of equipment, load development or bench equipment/technique.  It was the wind.  I'm carrying too many preconceived attributes into cast accuracy.  I can't even fathom shooting for accuracy without a 36 to 50 powder scope.  And to be perfectly clear, 99 of 100 military rifle shooters would kick my butt.  I appreciate the reality adjustment and hope I didn't offend anyone. Bill.

My addiction to gambling starts and ends with me spending $ to try a powder I’ve never shot before.

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David R. posted this 03 July 2022

Just my thoughts. I recently started weighing my bullets and culling them.  I haven't gotten very far with this yet. However I recently went to the range to test some .357 magnum loads in my Henry. I was shooting off a bench and using a chronograph. Ten shots were within 5 fps with three duplicates. I'm used to seeing a tight velocity spread with black powder but not so close with smokeless. I was impressed. Unfortunately I was having trouble with the sight on the rifle and stopped the test because I couldn't see well enough to aim precisely and it was clear that I had the wrong front blade on the rifle.  I intend to take this up again when I have an opportunity. For my own information I'm thinking that I will load some culls (no visual flaws, just outside of weight parameters) and do my own comparison. Who knows....may not be a nickel's worth of difference, but I will have answered the question for myself. 

I only recently learned that temperature effects weight. I have started monitoring my temperature more closely and have far fewer culls as a result. Just my 2¢ worth for today.  

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Bud Hyett posted this 03 July 2022

One thought in all this testing; how do we test the shooter on the day the test is being performed? This question was asked me many years ago at Windhill when I was complaining that the rifle was not repeating groups from the previous week. Ed Doonan told me when he started serious load development, he shot his match .22 LR for a few groups to be sure the anomaly was not him. 

Since then, my first testing is with a BSA Martini International with a known lot of .22 LR match ammunition for that rifle. If the groups are repeating from previous days, then I know I am ready to test. This means taking another rifle to the range and more targets. But I usually spend an entire day at the range and this is not a bother. 

Farm boy from Illinois, living in the magical Pacific Northwest

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Wm Cook posted this 03 July 2022

If you’re after small bullet weight deviation I think it’s something that you have to keep working as it. Even those that don’t sort for weight have their methods wired in to do the same thing the same way every time. I’m starting to learn that cadence / temperature is kind of important. As an off topic question I have to ask what powder you were using David? 357 Henry sounds like a whole bunch of fun. Bill.

My addiction to gambling starts and ends with me spending $ to try a powder I’ve never shot before.

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John Alexander posted this 03 July 2022

I commend Bill on suggesting a joint testing effort and joint discussion. Since Bill outed me as the guy who suggested trying it I think I should at least comment. My suggestion was probably not a realistic suggestion. Not because of all the reasons above which can be easily overcome by anybody who really wants to find out, but because there just isn't much interest in finding out when you already know you know the answer and are happy in your belief.

Porthos and Shopdog say just cast good bullets.  Everybody agrees. Nobody is advocating using bullets that enlarge the group,  But how do we know how much variation in weight will enlarge the group? If we are casting excellent bullets, do we still need to sort by weight?  

By the time most cb shooters are averaging five shot groups under 1 moa they have learned to cast excellent bullets that vary no more than two to five-tenth of a percent. BUT THEN most sort by weight down to one-tenth of a percent variation (0.2 grain variation in a 200 grain bullet.) Most actually sort to 0.1 grain and some to 0.05 grain.  The question is -- does this sorting shrink groups below what they would have been if left with 0.5 grains of variation?

Running the simple test Bill suggested would answer that question but with a couple of exceptions all the shooters I have discussed this with have NOT tested to find out. They just sort.

100 bullets used in the test and one day weighing, loading and shooting would probably tell, to a high degree of confidence,  whether sorting improved groups but why bother if you already know that sorting improves groups no matter how good the bullets were without sorting.  I don't understand this mind set, but that's the way it is.

John 

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David R. posted this 03 July 2022

Accurate #9 was the particular powder. It was with a 170 grain SWC. Velocity was in the 1,790s. I had lead fouling afterwards and that bullet didn't feed very smoothly. I won't be using that combination again. 

Regarding the "fun" of the Henry, I have to confess that I haven't had much fun yet. I hope that it will get better. I considered posting my saga, but it's far from over and I'm not sure if folks are interested in my silly story. 

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Wm Cook posted this 03 July 2022

If there’s lead in the story maybe you should start a thread. One of the most fun cast rifle I owned was an old Marlin 336 lever gun in 35 Rem. Had to go to receiver sights. Eyes are too old to connect the rear sight and the front post. Didn’t need to do a lot of sorting bullet weight for that one . Nearing 1800 fps with your Henry might be just a tad too quick to keep leading away.

My addiction to gambling starts and ends with me spending $ to try a powder I’ve never shot before.

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porthos posted this 03 July 2022

i'm using reciever sights on several of my military rifles now. it is no longer working out very well. still fighting going to scopes!!

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Rich/WIS posted this 04 July 2022

The NRA Cast Bullet book has an article by Frank Marshal Jr about this.  In the article he discusses both weight segregation and orientation, as well as results by visual inspection only. There is a definite and significant difference in accuracy depending on whether segregated by weight and oriented, segregated by weight and only by visual inspection.  His results were based on over 1000 shots fired and make a very strong case for both weight segregation and orientation when looking to maximize accuracy.

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Larry Gibson posted this 04 July 2022

Weight sorting for precision [best accuracy] loads

It depends on the weight of the cast bullet to begin with. Most weight sort thinking those bullets that weigh the same or with a +/- will shoot the best. I've learned that while that method of selection will give better accuracy it will not give "the best". As I weigh each bullet, I visually inspect the bullets first. Any visual defect, no matter how small, is cause for rejection. I then weight sort to eliminate those very light bullets that passed the visual inspection but obviously have a void inside. I then put the bullets into small plastic bowls of .1 gr increments.

I'll explain with 7mm to 32 caliber bullets of 150 to 220 gr as an example. Many who weight sort will kind of "graph" the bullets out by lining them up in tenth grain increments that are consecutively numbered and straight across the bottom. What you end up with is a "bell curve" shape of bullets. The curve starts out curving up, peaks out and then curves back down almost the same as it went up. The majority of the bullets in the curve will have a 1 to 1.5 grain difference in weight. There will be some that are much lighter and a few heavier. That is what you get with "good" cast bullets.

Using a quality alloy that will cast excellent bullets is also paramount. This is why straight linotype and #2 alloy are most often used. They give excellent and uniform fill out, consistency of weight with fewer defects. Some batches of COWWs will also if the antimony and tin percentages are sufficient and balanced. Alloys in these smaller caliber bullets that give a lot of shrinkage will never cast "excellent" bullets no matter how good they look. The reason is we cannot control the shrinkage and where it occurs on each bullet. Slight shrinkages that are in different places on the bullet are undetectable by visual or even precise measurement and they mean a slightly unbalanced bullet. Might not seem like much but at higher RPM and/or at longer ranges of 200 yards and beyond it is readily detectable on target by enlarged groups and poorer accuracy. Complete fill out in the mould and minimal shrinkage is needed for a quality cast bullet that will give the best accuracy.

Weight sorting the visual inspection passed bullets with "excellent cast" bullets gives a weight sorted curve that rises sharply and then levels off with several weights (three or four of .1 grain increment) having about the same number of bullets. The curve then falls sharply to just a few heavier bullets. There is no downward "curve".

When I got the 4 cavity NOE 30 XCB mould I ran this test with Lyman #2 alloy;

I cast 531 bullets

1.9% were rejected for visual defects

8.6% weighed less than 157.7 gr (some as much as 2 gr less that obviously had internal voids I could not detect through visual inspection)

3% weighed 157.8 gr

4.5% weighed 157.9 gr

5.9% weighed 158 gr

18.7% weighed 158.1 gr

19.3% weighed 158.2 gr

21.6% weighed 158.3 gr

14.7% weighed 158.4 gr

1.8% weighed 158.5 gr.

I then loaded 10 shots of each increment (157.8 gr to 158.5 gr) to test at 300 yards.

Test rifle was my 30x60 XCB. The NOE bullets weight 164 gr +/- when fully dressed and were loaded over 53 gr of AA4350 which runs 2900+ fps out of that rifle. The incremental test loads were fired consecutive by weight with the barrel cooled, cleaned and then fouled with 2 fouling shots prior to the next increment test. The results were then graphed out for a simple visual comparison.



We see the lighter weight 157.8 and 157.9 gr bullets were not as accurate. The lighter weight bullets giving indication to probable incomplete and inconsistent fill out and/or shrinkage or that they have small void(s) in them.  The "heavy" end of the bullets (158.0 through 158.5 gr) gave consistent accuracy (precision) at very close to moa at 300 yards. I have run this test several times and with cast bullets in the 150 - 180 gr weight range I select the heavy end of the weight sorted bullets +/- .2 to .25 gr. With this weight range I use the 157.8 and 157.9 gr bullets for foulers and the 158.0158.1 bullets for sighters. The 158.2 through 158.5 are then used in matches and other tests where precision is measured.  For the best accuracy at this level of high velocity the top half (158.3 to 158.5 gr) of those selected bullets almost always give the best results, particularly at 200 and 300 yards.

With other weight ranges I like wise run a similar weight sort test and now select the heavy end of the match selected weight sorted bullets for accuracy/precision use.

LMG

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

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Larry Gibson posted this 04 July 2022

Weight Sort 30 XCB Cast Bullets

Ten years ago I thought I was casting pretty good bullets, excellent in fact.  However. the more I got into shooting cast bullets at HV I found while I was casting good, excellent bullets I too hit the accuracy wall that many allude to of 1 1/2 moa +/-.  I also found that when those cast bullets were pushed to really HV (2500 - 3000+ fps) they did not do as well as expected.  Back then I was weight sorting as we've all been told to.  If you line them out by weight you get the so called "bell curve".  In proving insanity, I, like you and everyone else, then did the same testing of each .1 gr testing over and over again expecting different results.....we all got the same results; accuracy was not really improved via that method no matter how many times we ran the test.  If you are asking us now to run the same test and think the results will be different?  It wouldn't happen, as the results will still be the same.

Proper weight sorting 

Let's assume we have a mould that will cast perfectly even bullets in all dimensions.  Not an assumption but fact is that mould has a finite capacity for any alloy.  Thus, if we cast with a good alloy giving the best fillout then only those that weigh the heaviest will have filled the mould out as completely as possible.  Any bullets with less weight are then not dimensionally the same.  We may not be able to measure other than weighing that difference, but the difference is there in lighter weight bullets none the less.  Understanding the difference in weight (mass) is there but it is not predictable and most often not perceptible except by weight sorting.

Never too old to learn.....

I recently cast 542 NOE 30 XCB bullets of #2 alloy.  I have just completed weight sorting them.  In the next post I will show the graphed results of the weight sort which should aptly demonstrate what I'm saying.  Have to copy, download, etc. so it will be an hour or so.

Here is the results of the weight sort.  542 bullets were cast of Lyman #2 alloy and WQ'd.  They were then aged about 12 days before I got around to weight sorting.  Here is my set up for weight sorting.  I visually inspect each bullet for any defect.  If any is found that bullet is rejected to be melted and recast at a later casting session.  Those that pass my anal visual inspection then have any remnant of the sprue cut off.  That is done on the lead block with a sharp blade on the pocket knife.  The bullet is then weighed on the Redding balance beam scale.  While waiting for the beam to settle I then visually examine and sprue cut another bullet.  With the magnifier in front of the scale I can readily and accurately see what the weighed bullets exact weight is. The bullet is then placed in a bin for that weight. 

 

Of the 542 bullets weighed 22 were rejected for a visual defect or because they weighed less than 156.9 gr which means the weighed ones had passed the visual inspection but still weighed way lite.  The remaining 520 XCBs were weight sorted into separate bins of .1 gr increment from 156.9 gr to 158.0 gr......a 1.1 gr spread.  We don't know where in or on the bullet that difference in weight is missing from.  The missing weight is what creates the imbalance.  I suspect voids in the alloy are not the problem, but rather other aspects are which I have previously discussed. 

The weight sorting is showing us the 113 bullets of 157.7 gr, the 124 bullets of 157.8 gr and the 119 bullets (I'll put the 158.0 gr bullets in with those) of 159.9 gr weight has the highest weight/mass of alloy in them.  Since the curve dropped off suddenly we see those weight bullets are the most consistent and the best the mould will produce with that alloy.  Those 356 weight selected bullets will be used for best accuracy. 

The 157.6 gr bullets will be used as fouler/sighters as I expect they will give very good accuracy also given only a .2 gr +/- difference in weight.

Had we lumped all the visually selected bullets into one group 70% would have been with the excellent bullets, another 15% would have been with the fouler/sighter bullets and the remaining 15% would have been with bullets having a weight/mass difference of 1.1 gr.  Now, had I done that I probably would have got nice 1 1/2 moa groups with 7 +/- shots going into moa or less and 2 -3 +/- shots going out of the group in the 1 1/2 moa +/-.  How many of you shoot groups like that with bullets only visually sorted?   

It is with such weight sorted selected bullets (the 157.7 to 157.9 gr bullets) that I am able to hold moa accuracy to 300 yards and beyond with a 2900+ fps velocity. 

 That is how I weight sort the bullets I use for precision shooting and why it makes a difference.

 LMG

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

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John Alexander posted this 04 July 2022

Larry,

Excellent set of experiments and nice reporting. Very impressive high velocity results. Thank you for taking the time to repost.

I hope your work inspired other to examine other aspects of cast bullet accuracy.

John

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Wm Cook posted this 04 July 2022

Great detail Larry, thanks.  You've given a lot of your time to helping others.  I and many more like me appreciate your work.  My hats off to your experience and work ethic.

My addiction to gambling starts and ends with me spending $ to try a powder I’ve never shot before.

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Ross Smith posted this 05 July 2022

Larry: Do you mix or keep the "kept" bullets separated by weight?

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Larry Gibson posted this 05 July 2022

Ross

I mostly just shoot them as "separated by weight" simply because they already are 'separated".  I've over 3,000 of them out of the 30x60 XCB at high velocity.  Don't know how many but probably around 2,000 out of my M70 match rifle shooting mostly for score on CBA score targets.  I run those around 1800 - 1900 fps depending on which powder I'm using.  Minus the very small number of the top weight, I generally get the best accuracy score wise with the top weights having not more than a .4 gr weight spread. 

Using the top end weights which have the most complete fill out is the key as they are the best balanced. 

LMG

CBA score targets shot not too long ago.  There was a slight wind (probably 1 to 2 MPH0 coming out of 2 - 3 o'clock.  Bottom left is a fouler/sighter target.  Top targets i held for the wind.with both being 5 shots.   I moved the scope elevation (1/4 moa) between targets.  Bottom right is two separate 5 shot strings.  The first i held for the wind with the shots centering over the 10 ring.  The second I held center X just to see if the wind was drifting/affecting the bullets as much as I was holding for.  It was.

 

In shooting for a 10 shot group with my HV load for this rifle I shot this target.  Bottom two shots were sighters.  I made elevation/windage correction in the scope then shot 10 for record.  I chronographed the 10 shots "for record".  Obviously, the care to which I cast the bullets, inspect them and weight sort them pays off.

BTW; IMHO, shooting for score is a lot more difficult than shooting for group.

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

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