Guys, I have a 18" ARP 6.8 barrel with the ARP superbolt. I have been shooting S&B 115 FMJ factory and Hornady 120 SST factory without any problems. Today I shot some rounds I hand loaded for the first time, through a chronograph. I loaded 120 SST, S&B brass, AA2200 powder at 25g, 26g, 27g, 28g. I shot 5 of each and every single one short stroked. The 28g loads got the same velocity as the S&B FMJ's factory loads.
Any ideas on why my hand loads are short stroking?