I have a Uberti 1866 "winchester" carbine and a Uberti 1873 carbine, both in .44-40. The 1866 will handle full charge black powder loads and standard factory smokeless loads with no problem. Just no hot or high power loads and you are fine. All modern made firearms have to be able to withstand SAAMI (standard factory) loads. By the way, the same advice goes for the 1873 too.