I have been loading 165gr NP's ove 58.5 grains of H4350 for a few years and getting velocities in the area of 2950 fps. I started on a new 8lb jug and started low to rework the load. The best accuracy was at 57.5 grains. I built a few more to get velocities and was suprised to see an average of 3090 fps. OAL, gun, primer, bullets, and chronograph are the same. Drops seem to match the velocity at 620 yards. Any ideas why the velocities suddenly jumped? The brass does not show signs of excess pressure. Bolt lift is normal.