I am looking at possibly purchasing a Joslyn Carbine Model 1862. Like all Joslyn 1862 models it has the brass mounted hardware and patent dates on top of the breech. The only issue seems to be that that it has the later model 1864 model spring loaded catch on the breech block and the shrouded firing pin. There is an acceptance cartouche on the stock. Could this model 1862 been arsenal converted to a model 1864 style breech block tensioned release and shrouded firing pin during the Civil War as a transition model, or is this just a post war improvement? I do not know enough about these interesting carbines and would appreciate any information from people here better informed than myself.