I have the same rifle barrel. I shoot the same thing. I like 100 grains of powder. The max is 110 according to Green Mountain Barrel Company. I personally think this is a level done for legal reasons. GMB makes Knight barrels. You can shoot 150 grains of loose powder safely out of them. I see no reason the GMB .45 could not do the same. I would put the max if I were shooting at 120 grains of loose powder.