I gave the H&R cartridge some thought. After all I have a stainless 4" S&W J-frame in that caliber. But I shoot a lot of S&W Long ammunition in it for hearing's sake. And that is why I stuck to the shorter cartridge for the Remington. Trying to keep loads below mach 1. I think I could load the Long case to pretty high velocities in my rolling block. My testing with AA #7 showed close to 1500 fps with 100 grain cast with no sticky extraction or primer problems. While not a deer rifle my little rifle would put the hurt on a coyote size animal at 1,000 fps.
Still haven't sighted in the new load. Maybe today.
Jim