I got my Ruger American 6mm creed cut to 16.5 and it’s now keyholing at 50 yards and all over the damn place at 100 yards if it his paper. With the suppressor, no suppressor, hornady black and precision hunter all had issues. It’s in a mdt chassis. Could the chassis cause it, maybe I didn’t tighten down the bolts enough? bad cut and thread job? I believe the Americans are 1 7:5 twist