Re: .300 Win.mag./H-1000
Don't worry about the powder charge at all. I am loading a Mark V 270 Weatherby with 73 gr RL 22 with 130 gr Barnes X and 74 gr RL 22 with 130 gr TSX getting 3397 and 3461 fps respectively. I loaded up to 74.5, but the groups opened up from 1/3 MOA to 2+ MOA. If it is working, don't fix it. H1000, as you stated, should be a more stable choice.