Thread: Unusual 223 results

Here is a shot string fired from my 223 range rifle. 26" SAMMI chamber Barrel is at about 100 - 150 rounds and is shooting consistently 0.6 MOA. Load is in new but prepped Starline brass, WRE primer, 24.0 2208 with 88 ELDMs at 63.0mm COL. GRT velocity projection is 2790 fps at 58,000 psi. Actual velocities have been 2780 average over 20 rounds with an SD of 13-15.

So I was very puzzled yesterday to record the following string: 2791, 2868, 2800, 2884, 2807, 2879, 2873, 2855, 2878, 2794, 2843, 2782. That's an ES of 102 fps with an SD of 39

Sorted the velocities are 2884, 2879, 2878, 2873, 2868, 2855, 2843, 2807, 2800, 2794, 2791, 2782 and it seems to me that I have a high batch of rounds, all of a sudden the velocities "jump" 40-80 fps.

My first thought was the powder measure had gone awry, so I pulled the remaining 20 rounds of the batch only to find a maximum variation of 0.3 grains, one round a 1/10th over and 2 a tad under. Following that exercise I'm totally out of ideas . . .

Thoughts folks?