I had one of these a few years ago that I tried to convert to .45 Colt. A Uberti centerfire cylinder dropped right in, but the hammer has an off-center firing pin for the percussion cylinder and the hole in the recoil shield is also off-center to prevent such a simple conversion. A centerfire firing pin was swapped out on the hammer and I egged out the hole in the recoil shield sideways a bit to accommodate it. I slid five rounds in, stepped outside, thumbed the hammer back, and squeezed one off. The recoil seemed a bit more than it should have been, so I looked things over, opened the loading gate, and discovered that three rounds had been fired... Two of them were sans primers, and the third primer was lodged in the egged out recoil shield hole. Apparently, the hole was just large enough to allow the primer to blow out of the primer pocket, swage through the hole, and escaping gases would blow the hammer back, rotate the cylinder, and the hammer would then drop on the next round, continuing until either the trigger was released or the thing jammed up, as it happened to do. I debated trying my hand at welding up the recoil shield, but finally just reinstalled the percussion cylinder and original firing pin, and it worked just fine as a percussion revolver again. Since BP doesn't have enough pressure to produce similar results with the percussion cylinder, I've often wondered if it would have worked if I had used black powder .45's instead of smokeless rounds.