I have a Uberti made RM Conversion chambered in 38 Spec that handles black powder fine. Shoot Snakebite cast bullets and use FFF Goex. I bought it through Taylors, but the Cimarron issued ones are no different. Only difference basically is the barrel, octogan vs round. The 51 Conversion shouldn't have any other problems any other conversion has had that can't be rectified, ie arbor fit, minor timing if needed. As FriscoCountry posted "The 38 Spec open tops will handle 38SC and 38LC just fine". Any jamming will depend on luck of the draw as in any percussion/conversion on the market. Most run fine out of the box, but a few once in a while need some timing work that isn't hard to fix.