According to the techs at TC, Trapdoor loads are the only loads you should use in a Contender. The best thing about the .45-70 is how much power you get with low pressures resulting in fairly mild recoil. H4198 gives high velocities and low pressures with Trapdoor loads. IMR4198 runs at higher pressures so don't match H4198 data with IMR4198. My favorite load will match Winchesters factory load rifle velocities using a 14" (12"+2" brake) barrel. I hope you enjoy the new gun!

Here is some handgun data from Hodgdons site showing how well H4198 stacks up against other powders for velocity and pressure. These loads are for a 300 gr Sierra .458" JHP.

Varget 57.0 1512fps 16,300 CUP 63.0C 1821fps 23,800 CUP

H335 57.0 1645fps 17,500 CUP 63.5 1926fps 27,400 CUP

H4895 58.0 1654fps 16,500 CUP 62.0C 1874fps 21,000 CUP

H322 54.0 1699fps 18,100 CUP 60.0 1940fps 28,000 CUP

H4198 45.0 1774fps 16,700 CUP 55.0 2076fps 27,600 CUP

This load is safe in my barrel but may not be in others. Start low and work up. This is a 5 shot group.