I think you’d be best to replicate the test at least once more. You really need at least 3 replications for scientific data anyway, and when you’re looking at a ladder test it’s best to have enough good data that you can rely on it and not try to see pictures in the clouds. Pretty sure someone else has stated it but is this virgin brass or are there any differences in number of firings? Might look at water sorting some brass to be sure that isn’t another variable. In general most of these velocities seem pretty flat so it looks like you’re in a good charge range.I'm confused?
Did a 10 shot ladder test for my Ruger No. 1 6.5 PRC.
6.5 PRC, 7.5 Twist, 27"
124 Hammer Hunter
Federal 210, ADG Brass turned to .014" thick (rifle has a .295 neck).
RE26 starting at 58 grs, increased .1 grs to 58.9
Brass has been prepped in detail, trimmed to .001" length.
I've done many ladder tests, bur this one has me confused.
58.0 = 3343 FPS
58.1 = 3337 FPS
58.2 = 3301 FPS
58.3 = 3309 FPS
58.4 = 3300 FPS
58.5 = 3289 FPS
58.6 = 3304 FPS
58.7 = 3232 FPS
58.8 = 3397 FPS
58.9 = 3304 FPS
My confusion is why did I get 30+ fps faster with .2 less powder. Haven't see that before?
Load 7 was 70 fps slower, I'm attributing that to a bad read by the chrono.
Throwing out load 1, 2, & 8, I get ES of 19, SD of 6.2
58.3 grs seems to be the flat spot and I am happy with velocity, will start playing with seating depth with that load.
What are your thoughts?