I have an 1860 pietta, so I bought one of the brass 1851 .44 just to try the barrel. It fit perfect, I also changed the grip frame the same time, and both fit without any fitting required. So basically I have an 1851 with a 1860 frame. I mostly own NMA's and never really liked open tops that much, but Now after the change I love my little .44 bastard pistol. It has become my favorite.