3.7-3.8 with a 158 BB SWC at 1.465" is really nice in my 6" 686. That moves it at about 759fps for a 120 PF is you're an icore shooter. You may want to buffer this with a couple of tenths depending on what your SD is. Also, I've found 244 does just about the same with this bullet, maybe a few fps faster but in the same ballpark.