You can guarantee to avoid double charge by using "slow" powders, H110, Enforcer, 2400 but those probably will put you over 1200. I've been using Enforcer lately and had to bump charge almost to powder manufacturers max otherwise it was real messy but bullet is almost sitting on the powder so there's no way case can be double charged. It produces about 1340 fps out of my 7.5" (in the manual they state about 1900 !). I've also tried 4227 - also good case fill and even less fps. So you can try 4227 or it's Hodgdon analog. Recipes available at hodgdonreloading.com. Good luck.