I've just started reloading for my S&W 929 revolver using W231, Federal primers, 125 grain RN bullets from BBI, and range brass. Rounds with 3.8 grains of powder chrono'ed ~980 fps, rounds with 4.0 grains of powder chrono'ed ~1020 fps. This recipe has been relatively succesful for my M&P. However, 15-20% of the primers are backing out when used in the 929. Does anybody have any thoughts about why that is happening?