I do a lot of 100 yard shooting with my Thompson Contender 44 Mag, 14 inch bbl with 4x scope. It shoots best with heavy bullets and max loads of W296. I can get 1.5” groups, but not with other powders or lighter bullets. My best load so far is with the 265 gr bullets made for the 444 Marlin. I have not tried the Hornaday 300 gr XTP HP yet, but I have some to try.
Those group well with max loads from my 8" Dan Wesson. I need to get a .44 barrel for my old Contender.