I have a TC Black Diamond super xr .45 with the 1:28 twist. It loves Powerbelt 275gr hollow points and 120gr T7 3f, shoots 3" groups at 100yds with my poor eyes and a williams peep and front fire sight. Using a scope it's more like 1". Maybe this will help, but since we're talking different rifles, it could be apples and oranges, who knows, but it may be worth a try. In the past with a couple different rifles, just using a wonderwad between powder and bullet made a difference in accuracy. hth, Tim