I just bought a Uberti Colt 1849 pocket pistol. It is a great shooter, but I have noticed that when I push the wedge in all the way, the cylinder locks up. If I leave it a bit "loose", it works fine.
Typical short arbor. Several diy ways of correcting this, from jb weld on the end of the arbor to making a spacer for the barrel lug arbor hole.
Use the 'search' function and you find several articles here on this problem with ways to repair.