I loaded the exact same bullet and primer combo. Shooting from a Glock 34 I was using 4.2Gr of Winchester 231 and an OAL of 1.155. Velocity average was 1098. I had loaded up to 4.5 grains of 231 with Velocity around 1150. But the G34 has a bbl length of just over 5 inches so that kept the velocity up there your millage may very. Winchester 231 is a good overall powder, measures well and is difficult to over charge. I have since moved to 147 gr and Tight Group but would not suggest Tight Group for a new re-loader.