Boonerbuck; They do just fine in a 1-10" twist. I shoot them in my '06 at just shy of 2700 and they group into ½" or so. I'm using Norma MRP at 58 grains, but you should start at 55 and work up carefully. If No Norma Powder, try RL 22. As a Matter of fact, I loaded some in my 30-338, which has a 1-12" twist. They leave the muzzle at 2990, and group about ¾" at 100. Regards, Eagleye.