Charlie98
Member
Hornady recommends a muzzle velocity range of 850-1,550 fps for the 250gr XTP/HP.
That's kind of why I recommended IMR4227 or 2400, as opposed to W296/H110, to keep the speeds under control. OPs' rifle appears to be a 20" barrel, not the 16" of my brother's Trapper... but my H&R has a 20". Based on the results I get out of my 20" Marlin in .41MAG, a mid-range charge of W296 would put him over 1600fps... I get 1750fps with 21grn W296 and the 210grn XTP in the Marlin. Using the slightly faster IMR4227 or 2400 helps me to keep the speeds under control while still getting a good case fill and good burn.
6.5grn TiteGroup and a 250grn cast SWC gave me a mere 1050fps from the H&R...
9.0grn Unique gave me 1100fps...
20grn IMR4227, 1175fps.
Moving to heavy bullets...
9.5grn Unique and a Montana Bullet's 270grn cast gave me the same target velocity of 1100fps in the H&R,
15grn 2400 1125fps, 20grn IMR4227 a little more at 1150fps.
Looking at the data for jacketed bullets (Nosler, etc...) they use a pile of different powders that would work... discounting the fast burners (that is, anything faster than Unique...) you have suggestions of AA's #5, #7, and #9, LIl'gun, BlueDot, Enforcer, AA5744 (which some use in pistol cartridges with success...) HS6. That data is for pistols, of course, but starting at Unique and going slower... for the longer rifle barrel... you can maximize the load. If you were just poking holes in paper, anything in the Unique range would work well, to include some faster powders like W231 and TiteGroup, but once you start going heavy, or need something for hunting or longer ranges, the better choice is something in the IMR4227 range. Just MHO.