I have a similarly finicky early model Browning x-Bolt with a 22" - 10" twist barrel. That will consistently shoot Sierra 200 gr. Game Kings into about 1 moa or better. My load is 54 grains of H4350 for 2650 fps that still has 2075 fps and 1912 ft lbs of energy at 400 yds. Shoots 200 gr Nosler Partitions equally well.