Your Uberti 1876 is a copy of the Winchester 1876 Centennial rifle. The rifle is a scaled-up 1873, similar link system and feeding system. 45-75 cartridge was designed because Winchester could not stretch the 1873 action enough to accept 45-70 cartridges.
45-75 was based on a necked-down 50-70 case.
On the Ubertis, function is good. Wood is just OK.
In general, an OK rifle. I have not hears of any major issues with the rifles.