momo said:
1.PF for 125gr Sierra FMJ RN at lowest grain was still average 135 in one gun and 130 in the other. No feed or cycling issues. Can I go below the recommended starting grains now to try to get closer to 125?
What was your minimum velocity and power factor? What was your extreme spread ... and how many rounds did you run through the chronograph?
It must have been in one of your other threads where I quoted the IDPA rule book on how they test ammo for power factor. This is the protocol for larger matches, like regionals; I don't know if any clubs bother at their regular competitions, but you might as well have ammo that you know will always pass if you happen to shoot a big match.
You show up ... they pull three rounds at random from your ammo box/bag and shoot them over the chronograph through your gun. Two of the three must make the minimum power factor. That means, depending on the extreme spread, an average of 130 or 135 might not be good enough because you can't count on the random pick getting rounds that are near the middle or high end of the pack.
For this purpose, I want to know that the
worst round will make power factor, and then try to minimize my extreme spread so that the faster ones aren't a whole lot faster. If you'll be alternating guns for competition, you also want to be sure that your
worst round will make power factor in the slower gun.
What were the slowest velocities you recorded in this round of testing?