I reamed mine to 460 sw. It has a large chamber and swells cases at the base. I just size the front part and let it go. It will do about 2800 w 200 gr gummy tip Hornadys. Currently playing with powder coated 500 gr Lee and IMR 4198. I have the barrel on a reciever with a Handigrip stock. HEAVY stuff is not pleasant with the steel butt plate. Have had better and worse accuracy wise. With the use of. O rings in the extractor groove you can shoot rimless rdssuch as 45 GAP, 45 ACP, 45WinMag. The list is. afaik is the previous 3 plus 45 cowboy, 45 Schofield, 45 Colt, 454 Casull, and 460 SW. I ain't gonna tell you that accuracy will be stellar with some of these, only that it will shoot them. All in all it makes a good light carbine that speaks with authority, even in 45 Colt, with proper handloads. Mine might be the last to go because it will shoot nearly anything straight wall 45 you can find except 45 Auto Rim. Use your own judgement.