B14R Ammo testing, to sort or not to sort, THAT is the question....

[docohm]

Ammo test, to sort by weight, rim thickness or both? I just got in a new batch of SK Long Range Match so first I sorted 250 rounds by weight, then I took all the ones of a mid-range weight and rim thickness sorted them. Went to the 50 yd range today and first shot unsorted, 5 groups of 3 rounds each. Then shot the sorted by weight, then the sorted by weight and rim thickness. All 5 groups of 3 rounds each. Wind was very light at my back. Rifle was B14R CF w/ 18" barrel. I'd already determined that it like SK LRM best!
One of the guys there also had his RadarLab device so I also got a 10 round measurement of each group. This was NOT the same groups I shot, it was a little later in the day.

Results (for those of you who don't want to study the picture):
Unsorted 2 groups (of 5) that are 0.300" or smaller, Avg Vel- 1135, SD-13.5 ES-47.
Weight sorted: 2 groups of 0.300" or smaller, Avg Vel-1126, SD-13.8, ES-46. (Not much better than unsorted!)
Rim thickness sorted: 3 groups of 0.300" or smaller, Avg Vel-1128, SD-5.8 !!!, ES-17 !!!

So.... Looks to me like rim thickness sorting is the way to go. Next test: thickness sort the WHOLE box of 500 (less the few I show today) and try them out for accuracy.

 

[justin amateur]

Weight sorting, rim thickness, overall cartridge length, been there, tried that, documented the results and chrony numbers.
3 different occasions, a full brick each time.
Absolute waste of time unless you are a bit OCD. Then it'll keep you occupied.
Many others, including a few with better math backgrounds in statistics have also.
They analyzed the results, produced graphs, published the studies.
The consensus: Sorting is a waste of time. Good way to kill an evening,
but y'er better off spending y'er money on better ammo.

The reason why it doesn't work?
You have no idea which variable(s) are actually causing the differences in results.
Is it primer/powder amounts or chemistry?
Is it bullet shape/seating/weight?
Was the bullet heel damaged on the assembly line?
Is it brass hardness/volume or crimp tension?
Is it a combination of any and all of those problems?

Rim thickness has no relationship to the true variables that actually cause trajectory spread.