Biggest problem with the brass frame Ubertis is they were in.38 Spl for a reason. The brass frame tends to stretch when fired with hot loads.
Needless to say, many gun magazines began to boast of using 13.5 gr of 2400 in reloads.
I believe I bought a stretched rifle as the used 1866 version I had rarely would fire, and the extractor hook would not grasp the cartridge.
The Uberti 1873 had no such problems with it’s iron frame.
If anyone buys a USED 1866 brass frame, make sure the bolt goes completely closed, and try to fire it before you pay for it.
Also, with reloads, the cartridge length is very important. Too short a round and the next one in the tube will cause a jam. Too long a cartridge and it will jam so the lifter will not lift it. I keep a small flat screwdriver at hand just for this problem with reloads. If the round is too long, I try to pry the bullet into the case far enough to clear the lifter. If too short, I use the screwdriver to press the next case back into the tube.
Never had a problem with factory loads.
Yes, these old guns, and their replicas, were never designed for hot loads. If some one wants to shoot hot loads in a lever gun, get a Marlin.