Hello, j-bird. Perhaps Uberti bored & rifled the barrel for modern .357/.358 dia. bullets? If so, the markings would make sense. You could call them to make sure..or slug the bore. I have a Kirst Konverter cylinder on my early
1970 era Colt re-make of the 1851 navy squareback. Had to use hollow-base bullets, but with light charges of Bullseye, it shoots quite accurate. These guns bring the FUN back into shooting!