Gents, this is not a spencer but an origional preabody saddle ring carbine in 56-50 caliber. I have already pruchased a spare rim fire breech block and spare rim fire firing pin. Now here is the fly in the ointment. I bought 10 each starline 5070 cases and 10 each 56-50 cases. The latter chamber easily. However some information researched leads me to believe that in the end I will end up trimming the 50-70 cases down to get the proper case length. I have been giving much serious thought to having the barrel rechambered to 50-70 to simplify getting proper cases and while this is being done, have the spare breech block converted to centerfire. Loading data I have seen indicates that for the carbine 55 grains of black powder with a 480 grain cast lead bullet should approximize the standard 50-70 carbine load. The carbine's bore is in pretty good shape and should make a good shooter. Any comments and/or suggestions are invited. Thanks, Frank