I bought an H&R Classic Carbine in 45 Colt a few years back and LOVE it. I've ran loads from mild to wild, starting with .454 RB loads at 900 fps, up to shoulder bruisers with the Lee C452-300 RF. The crescent steel but plate is very efficient at transfering recoil to the shoulder with minimal loss. It shoots very well with the 452-255 RF. I liked loading for the 45 Colt rifle that I just had to find a Ruger Vaquero (old model) in 45 Colt to go with it. The rifle is my 'Long Colt' and the Ruger is my 'Short Colt.'
When loading the 255 in the 4 5/8" Vaquero to 1200 fps, I get closer to 1500 fps from the 20" carbine. I've not benched the rifle, mostly just off-hand shooting. I will have to see if changing the forend pressure effects the grouping. This thread has me wanting to hit the hills again soon just to play with those two again