Ammolytics Bullet Sorting Experiment - Part One

Discussion in 'Reloading Forum (All Calibers)' started by Ammolytics, Feb 10, 2019.

  1. Ammolytics

    Ammolytics

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    Author here. The only reference I was able to find where Bryan Litz made this recommendation was in a rather off-the-cuff comment in the following YouTube video.


    As I mentioned in my article, I wasn't able to find any mention in the books of his that I own.
    If you are aware of another source, would you mind sharing? I'd love to read it.
     
  2. milanuk

    milanuk Gold $$ Contributor

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    @Ammolytics I'm not sure if there is a reference article, per se... but here is my experience.

    I'd gotten into pointing and meplat uniforming a little back when the 155.5 Fullbore still dominated FTR. The results that I got always seemed to be a little hit or miss, though. Then, when the 185 Juggernaut was the new hotness for FTR, I was setting up to trim the meplats on a batch of bullets (185s), to be followed by pointing. I measured a handful of bullets (OAL) and came up with an average length of... 1.367", if memory serves. I set the Giraud trimmer to trim to 1.365", and began trimming meplats. Bzzzt, bzzzt, bzzzt, nothing... bzzzt, bzzzt, nothing..., bzzzt. Hmmm... started measuring the ones where nothing was getting trimmed. Yup, they were more like 1.363, 1.361, had a few as short as 1.358". The tips still looked fine, carry on. A few more... bzzzt, bzzzt, bzzzt, then BRRRRZZZZTTT!!! Holy cow what was that? Thought maybe I just caught the edge of the cutter weird when I stuck it in. So I did it again... BRRRZZZZTTT. Okay, what the heck. Measured it, and it was *still* 1.370", even after having a whole bunch hogged off the tip, to where the meplat was well over 0.100"

    Ran across a handful more like that, as well as more that were short. I looked at the short ones, with their tiny little meplats (even before pointing), and the long ones, with what looked like the beginning of a wadcutter tip, and thought "there is no flipping way those are going to point up the same". So originally, I started sorting by OAL primarily so I could 'batch' the bullets before meplat uniforming and pointing. With some Skip Otto die shims under the lock ring on the .30 cal insert in my Giraud, it was easy enough to adjust the cut length between batches in a fairly precise manner.

    Eventually, I got to thinking, and realized that I really wasn't trying to make any one bullet 'perfect', and there was just enough variation that what was 'perfect' for one sub-lot wasn't going to work on another. What I wanted was to make the BC as uniform as possible. And I was already getting about 95% of that benefit from just sorting by length. Length is a contributing factor to the BC calculation, if I recall...

    By the time I was running 200 Hybrids, I was binning into batches of 5 thou... and still seeing 4 or even 5 batches, at that. Somewhere around then, I read a comment by Emil Praslick (formerly of the US AMU) that they (the AMU) sorted their bullets into 3 thou bins, for the same reason - to stratify the BC.

    At some point I did run a test, taking the longest bullets from a batch, and the shortest bullets from a batch, and a handful from the middle as a control, and shot them at a 600yd e-target. I don't think I have that plot any more, but it did show pretty clearly that while the groups did overlap considerably, there was a distinct difference in the vertical center of the groups between the long and the short bullets.

    The whole process, though, was tedious beyond belief. It got noticeably less miserable - though still not exactly 'fun' - with the advent of the SortEez tool, and then you can get into all sorts of fun stuff like multi-sort - sorting by OAL and BTO at the same time, and end up with really fun graphs like this:

    Screenshot 2019-05-24 at 12.57.54.png

    The above is for Berger 200.20X bullets, ranging from <1.500 to <1.521, all the same lot # (D24).

    Given that you seem to enjoy the whole data-driven process, I'd strongly suggest you check out getting a SortEez setup. It exports all the data to CSV files, which then can be pulled into either a spreadsheet like I did for mine, or into Python/Pandas or R or whatever your tool of choice is.
     
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  3. Pigdog

    Pigdog

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    Hi mate that video is where I also saw him mention it.
     
  4. johara1

    johara1

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    I guess it boils down to how accurate you rifle is, a 1/4 0r 1/2 min. gun you may not see any benefit. A .1 gun you can see the differences hold +- .0005 on bearing surface. With that caliper set up you are truly wasting your time. Weigh them if they are factory bullets, Good custom bullets Like Barts forget that. Weigh your primers..... jim
     
  5. Lbart

    Lbart

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    Monte,
    FWIW - back in the day… somewhere around 2001-2002 (before you started shooting F-Class) I got curious as to what I could do to get my 1,000 yard loads to group a bit better. So I took a 1,000 bullets from the same lot (can’t remember what they were) and measured the base to tip. I then shot the longest against the shortest in 10 shot groups at 1k. The only data I remember for sure was the longest ones grouped 6 inches higher than the shortest when shot at 4,000 foot altitude. At sea level there would have been considerably more difference. Since then I have always checked my overall length as my last step before loading.
     
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  6. milanuk

    milanuk Gold $$ Contributor

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    Larry, you know I blame you for getting me interested in F-class with your chapter in that book, back then? ;)

    It's *all* your fault :D

    FWIW if memory serves there was maybe 3/8-1/2 moa difference in the vertical group centers @ 600yd when I did my testing... so comparable to what you saw, I think.
     
    Last edited: May 25, 2019
  7. johara1

    johara1

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    if done right trimming and pointing is very beneficial in uniforming bullets and taking the vertical down to a minimum at long range plus it will raise BC. and lower wind deflection.... jim
     
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  8. Steve Blair

    Steve Blair

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    "If done right..."
    As in almost everything.
     
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  9. johara1

    johara1

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    Yes you have to be anal, and it pays off. If you can't see the difference your equipment isn't up to the task, or if you say that is good enough, you better get an other hobby..... never leave anything on the table.... jim
     
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  10. Steve Blair

    Steve Blair

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    Too true. The late Don Nagel once told me that he performed about twenty-five processes when reloading. He suspected that only about fifteen were necessary, but he didn't know which fifteen. ;)
     
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  11. Titan

    Titan

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    In Litz's Modern Advances in Rifle Shooting Volume 2. Chapter 3 in the Subsection "Bullet Sorting" right before the conclusion, he talks about using OAL as a proxy for meplat diameter and reducing BC variance by sorting by OAL, he sites an experiment with 185 juggernauts in this section.
     
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  12. johara1

    johara1

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    I know one thing I got less variance in 3000 Barts 6mm bullets than sorting a 100 6mm Bergers. Over .010 on the Bergers, +-.001 on Barts. You can make the Berger work, but you will have a lot of piles.... jim
     
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  13. Ammolytics

    Ammolytics

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    Thanks for finding this and letting me know! Vol 2. may be the only book of his that I don't yet own, which explains why I had not seen this reference.
     
  14. Titan

    Titan

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    No problem Vol 2. Is a good read. Keep up the blog I enjoy your content, the information and experiments are great.
     
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  15. Titan

    Titan

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    Unfortunately for 1000 yard f open class 6mm seems like a sub optimal proposition, I am sure his products are the cats meow for 600 yard bench rest. If he offered a high BC 7mm I would give them a go but for now the sorted and tipped 184 Berger seems like the best bet for my particular use case.
     
  16. riflewoman

    riflewoman Gold $$ Contributor

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    I would think that there are way too many variables in ammunition and precision shooting to be “controllable”. Most of these are beyond the control of the shooter no matter how sophisticated the equipment.

    For example does every primer ignite the powder the same? A member of the Palma teams once made a rifle with a smooth bore barrel for shooting BBs with a primer alone to see if primer batches could be selected. His results were inconclusive. Some lots with excellent velocity dispersion didn’t shoot well past 300 yards.

    Does every charge of powder ignited the same have the same pressure rise (burn rate)? I bet there are differences and the data is full of noise. How can that be controlled or influenced? Considerable money and time has been spent on solid fuel rocket “grain” (which are very similar to smokeless powder) design to minimize the instability during combustion. But I don’t see that level of effort in firearms propellants.

    How do these variables in bullet form affect the CG and Aerodynamic Center with and without yaw?

    Like I said, too many variables.
     
  17. riflewoman

    riflewoman Gold $$ Contributor

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    The resolution of the load cell is the same. The way the data os presented is the difference. It is my guess that the resolution difference is a result of mathematical conversion.
     
  18. johara1

    johara1

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    You may need to rethink the primer thing, long range bench rest weigh their primers for uniformity. You do have the tools to control the ammunition if you have the tools and knowledge and put forth the effort. Here again you you need a gun that is capable of repeatable sub .1 groups ...... jim
     
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  19. Ammolytics

    Ammolytics

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    Primer sorting is an upcoming article/experiment -- stay tuned! (Anecdotally, I sorted some CCI BR-4 by weight. When I tried to use one of the lightest as a fouler, it turned out to be a dud.)
     
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