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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    Hey folks,

    I wanted to share another article in which I attempted to measure the effects of bullet sorting by weight and length. While my results for these two experiments were somewhat inconclusive, I did learn a lot in the process. This is part one and I'll attempt this experiment again soon after I work out a few other variables.

    https://blog.ammolytics.com/2019-02-02/bullet-sorting-part-one.html

    I hope that this is of high enough quality to justify the time you spend reading it.
    Happy to answer any questions!
     
  2. Ned Ludd

    Ned Ludd Gold $$ Contributor

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    A very thorough and detailed analysis, thanks for posting. I think there is a definitive conclusion you can draw from your results; bullet length and/or weight variance is not the limiting factor in your shooting. When assessing return on time investment during the reloading process, identification of the major (limiting) sources of error is critical because time spent on other smaller (non-limiting) sources of error will generally provide a poor return on the time investment until the larger sources of error are addressed. I think your results indicate that you have other sources of error that are limiting precision to a larger degree than bullet length/weight variance. Once you identify those source(s) of error and address them, re-visiting bullet length/weight variance, or other typically much smaller sources of error may be more a productive use of your time.
     
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  3. Ammolytics

    Ammolytics

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    Agreed. I'm utilizing some of the data collected from these experiments for a root-cause analysis. I have the length/weight/capacity dimensions for each piece of brass used, among other things which may or may not prove useful. As I mentioned in the article, I was left with the impression that my bullet sorting practice needed work based on some issues in a previous experiment, so I decided to explore it in greater detail.
     
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  4. Zero333

    Zero333 Silver $$ Contributor

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    Wow that's one helluva experiment !

    So... Sorting some bullets is a waste of time. I usually measure base to ogive about 25 bullets from each box to determine if I should sort them or not. If I find a variance of more than 0.003" I sort them into a couple of groups so they're withing 0.002".

    Another thing that looked interesting in your experiment is the average muzzle velocity vs time.
     
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  5. damoncali

    damoncali Bullet Maker Silver $$ Contributor

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    This is great. Like any experiment, especially those done on a tight budget, it leaves as many questions as it answers, but I’m looking forward to more - great blog you’ve got going.

    One area I’d like to see verified is the impact of length on BC. Calculations show a small, but meaningful change with typical length variations in hollow point match bullets. It may be too small to reliably test without a tunnel, but it’s really the only bullet sorting that I can think of that may be worth the time.
     
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  6. JimSC

    JimSC

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    excellent idea but to draw any meaningful conclusions you would need to use a machine rest with a test barrel in a windless environment. From what I have been reading even a varying the pressure of your hold can affect POI and velocity SD. In the book Accuracy: A Brief Guide to Precision Shooting by Frank Troy he discusses when he was with the AMU there was a Sgt. Eugene Spradler whose full time job was to test guns and ammo. I want that job, I will work for free even. Anyway there was a 300 meter underground test tunnel set up with a bench and Sgt. Spradler noticed that even shifting one foot a few inches would cause the POI to shift. Dr. Troy believes that the shifting of the foot displaced the shooters center of mass altering the resistance to recoil which shifted the point of impact of the bullet.

    Bottom line is without eliminating the human and the environmental factors it would be impossible to draw any meaningful conclusions from the experiment. As I am fond of saying if all it took was a precise weighed charge to get single digit SD's we could all just buy a Sartorius Entris, switch to a fine grained powder and weigh it to .0001 precision and have zero SD's the rest of our lives. That not being true we have to work on our personal shooting skills and cannot get clean 200 scores simply by buying the right gear. Instead we have to earn them with practice and talent. I applaud the fact you are actually doing a thought out test however I think if you want to improve your scores the time and effort would be better spent on learning wind and consistent technique, without a more controlled test environment the results are questionable.

    I have bookmarked your blog and later on today will read the other articles later today, I am really interested in the Recoil vs Muzzle Velocity experiment
     
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  7. M995

    M995 T SNOOK Silver $$ Contributor

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    I'm more interested in the Accelerometer
     
  8. Ammolytics

    Ammolytics

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    Thanks! I didn't conclude that bullet sorting is a waste of time in this experiment. Rather, the process taught me that I have other factors to resolve first before I can expect a measurable result. I did notice that measuring by bearing surface was more consistent than measuring base to ogive, or at least it would be if the available tools were of higher quality. Either way, the measurements are not equivalent.
     
    Zero333 likes this.
  9. Ammolytics

    Ammolytics

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    Thank you! That's a great suggestion -- I'll add it to the list of future projects!
     
  10. Ammolytics

    Ammolytics

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    Ha! I'm glad you like that project -- it's definitely a popular one!
     
  11. Ammolytics

    Ammolytics

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    Thanks for the feedback! As I wrote, the results of a previous experiment led me down this path, so I wanted to shared that continued work and knowledge. Similarly, I was looking for practical effects (e.g. without a machine rest). Still, I agree with you completely that using a machine rest may be required to eliminate shooter error (of which I admitted to plenty).

    That said, there were plenty of other signals discovered in this process that give me more to explore. I'll be sure to publish those when they're ready!
     
  12. Culater

    Culater

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    Tagging along for this one
     
  13. davidjoe

    davidjoe Skunkworks Gold $$ Contributor

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    Sierra, possibly others, invested in a long underground testing tunnel. Sierra has been shipping factory retipped SMK’s for many years. You can readily see a separate tipping process was utilized. I’d be inclined to think that Sierra reached the conclusion that “proper” bullet tipping improved their bullets. (Many of us tipping our own are aware it can also cause damage).

    I’m also inclined to think the manufacturers have exhaustively tested to see what down-range results follow measurable bullet to bullet differences. While they’d never be expected to publicize what they found out at great expense over many years and many separate designs, we would expect that they’d ship product of uniformity that is well inside the line of materiality.

    The manufactures are ever-present supporting our events and acutely aware of the requirements to succeed, and I have to assume that they have already made all the easy improvements.

    I have taken a pair of pliers and mangled bullets in several different ways, and even removed some mass. Mashed others into the case, straight and obliquely. Smeared off polymer tips. You can get fliers, but it’s not as easy as you’d intuit, and those experiments obviously dwarf the inherent inconsistencies of focused match reloading.

    Wind calling and barrel condition become even more prominent goals after seeing just what we are working with.
     
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  14. Steve Blair

    Steve Blair

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    Doesn't require a tunnel, just accurate velocity measurement over distance. Like a high performance Doppler RADAR.
     
  15. Joe Salt

    Joe Salt Silver $$ Contributor

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    Your wasting your time weighing them, if you think that 1 or 2 grain weight difference will matter with 50 to 60 thousand pounds pressure you blowing smoke. Had one years ago that weighed 1.5 grains more in a box, and added it to my sighters it went in the ten ring at 1000 yards! But I do believe in measuring OAL of the bullets, try that.

    Joe Salt
     
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  16. Pigdog

    Pigdog

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    Interesting Joe Salt, litz recommends sorting base to ogive. Would you be able to elaborate on sorting by OAL instead interested to learn.
     
  17. Joe Salt

    Joe Salt Silver $$ Contributor

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    Piddog I normally do Bearing surface and I think shorter ones work best for what I have been seeing. But I also measure OAL. and separate them by thou of an inch. Know try chronographing the longest and shortest in a five shot string and see what you get.

    Joe Salt
     
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  18. David101

    David101

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    Next time you do your sorting use the gram mode. It gives the better resolution and accuracy. Some how you confused yourself and got it the wrong way around.
    From your paper
    From Chapter 5 of the FX-120i manual.

    From this you can see if you are in the gram mode 1 milligram is less weight than 0.02 grains hence it is the better range to use.


    • 0.001 g = 0.0154 gr
    • 0.02 gr = 0.0013 g
     
  19. dstoenner

    dstoenner Silver $$ Contributor

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    I worked at Lake City arsenal in the summer of 69 in quality control calibrating the ballistics equipment. We had an underground 200 yard range. The rifles used were Remington 700 and they were bolted into a concrete multi legged pier. The only human contact was the finger on the trigger. This was the range that military match ammo was qualified on.

    David
     
  20. Ammolytics

    Ammolytics

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    Author here. Would you mind clarifying what I got the "wrong way around"?

    Just above the section you cited in my article, I stated the following:
    "While I present the weights in grains, I actually measured in grams since this scale offers a bit more precision with that unit."
     

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