I have mostly just messed around with my 14" barrel. Just shooting blackpowder loads from it for huge smoke, boom, and flames. I've decided to try and get serious with it lately and have worked up some batches of test loads to try with smokeless powders. The only smokeless cast bullets I have on hand are some Meister brand 405's which are plain flat based bullets, and I do have a box of Cast Performance 440 gr hardcast that are gas checked. I've loaded test batches with the Meister's. I don't believe the gas checked bullets are necessary or will perform well through the Contender.
Since the Contender load levels for 45-70 are "Trapdoor Springfield" levels, I hadn't really planned on trying any gas checked bullets. I'm sure it wouldn't hurt anything to try them, as long as the pressures are where they should be. Gas checked bullets are for more pressure and velocity down the barrel really, at least in my opinion.
I also believe that the factory TC barrels are all 1-14" twist in 45-70. I'm inclined to believe that lighter bullets will probably shoot better, say 300-350 gr. I do have a 350 gr Lyman mold that I use to cast blackpowder bullets, I just haven't cast any from it for smokeless. My blackpowder bullets are cast very soft, and I'd probably harden them up a little for smokeless, even though the velocities are still pretty low.
I'm expecting to be able to take my test loads to the range next Sunday, and I'll post my results when I return. I have loads with IMR 4198, Varget, Benchmark, and IMR 4064. Will have to see if the barrel likes any of those loads.
I've also wanted to try the Remington 300 gr JHP bullets in it, those may shoot pretty well also.
