Rel 15 is normally THE powder for .416 Rems but the TSX is so long it drastically cut your powder room. I'm going to fiddle with some other powders in the Rigby too. The 7828 load was the first thing I fired in my gun and the first 3 rounds at 100yds went 1". It continues to shoot under 1 1/4" for three. These new CZs are great guns.