Why is my COAL varying so much?

[Danattherock]

I am using Redding Deluxe 223 dies. Lapua match brass all trimmed to same (+\- 0.001) length on my Forster trimmer. Flash holes deburred, which seemed pointless on this brass, champher/deburred case mouths, full length sized, etc.. Mica and case mouth brush inside all cases before sizing. All brass being used was weight sorted and found to be within 94.5-95.5 grains, heavier and lighter brass was bagged and labeled. FYI, of 100 Lapua 'match' cases, only 67 were within 94.5-95.5 grains. Press is the rock chucker. Made 25 rounds last week for my Barnes Precision AR15, my first reloading efforts. Shot them today, got 25 more cases and repeated the same recipe for retesting.

COAL on all twenty five 223 rounds are +\- 0.002 except for 6 rounds which were -0.007, -0.004, -0.003, -0.003, -0.005, and +0.006. Nineteen rounds were within 2.268 and 2.272, which I consider acceptable. I set my seating die up for a COAL of 2.270, which comfortably fits in my AR Stoner 10 round AR15 mags. Nineteen out of twenty five are acceptable, but the other six are further off than I want. How can I make all my reloads within +\- 0.002? Could the out of tolerance rounds account for flyers?

Am I overthinking things that won't matter much in reality? What bugs me is two of my 5 shot groups today with 69 SMK and Varget would have been 0.5 MOA without a flyer in each group, which opened things up to a hair over MOA. My goal for this particular weapon is 1/2 MOA, so I am eager to see what role (if any) this variance in COAL may have had. My intention is to get the load dialed in then start varying seating depth in 0.010 increments searching for a sweet spot. I just started relaoding last week, but having so much disparity from round to round just seems wrong.

Would appreciate any insight into the effects of said variances on accuracy, and of course would be interested in suggestions to remedy the issue. Case comparator needed, suggestions on which one? Saw the Sinclair and RCBS, but heard the much more expensive Accuracy One was better. Bullet comparator needed? These are things I know very little about if applicable. I have only loaded 50 rounds and appreciate any input.

Dan

[rboyes]

The variance is likely due to differences in bullet OAL. Its common to see differences in bullet length especially with hollow point bullets. Some people trim the meplats for uniformity. As long as the bullets are seated to the same depth then it shouldn't be much of an issue. Another option if it bugs you is ballistic tip bullets.

If you shot 5 shots and saw a flyer, it probably wasn't a flyer...it was probably just part of a larger group. Shoot a group with more rounds and see what you get. I can get some pretty good 5 shot groups, but I tend to see more consistency with 10 shot groups.