I got my 1866 Uberti sporting rifle (24 1/2" octagonal barrel) three years ago after being on order for another three years previously. Upon getting the gun it would not chamber rounds with the bullet nose catching on the bottom edge of the chamber, the problem I found to be that the lifter seemed to be to minimum tolerances in a receiver that was at maximum tolerances. When the lifter on its riser was at top dead centre there was enough clearance for the lifter to tip forward so that the bullet nose was catching on the edge of the chamber, easy fix I epoxied a couple of brass shims to the front of the lifter and filed to fit the receiver, job sorted.
Next issue was when working on load development I had a jammed action as live round had passed the retaining flange on the loading gate, seems like minimum tolerances on the flange combined with worn/rounded case heads and the round would slip into the action, again another simple fix, a shim of leather was epoxied 'tween the loading gate and the receiver plate sufficient to push the gate in a tad to hold the cartridges in the lifter.
Since then the gun has been faultless (touch wood) and is extremely accurate especially with BP loaded rounds and has had thousands of rounds through it since, in fact I have just loaded 100 rounds at the desk here with a 310 tong tool and Accurate 312 123 gn bullets and will be shooting them later this morning.
By rights I should have returned the gun with these faults but I didn't want to wait another three years for the replacement to arrive, fortunately the fixes were within my limited abilities and it has given me nothing but pleasure since.
I also have a Uberti 1860 Henry in 44-40 and an 1873 in 38-40 both of which I have had no issues with.