Leave it alone. 80 year old metal isn't the same as modern metal.
A new Uberti 1851 runs between $355 and $400.
I have no idea how a welder would tackle that job, but if you did go the welding route, I think the entire frame would have to be annealed afterward, then re-hardened. I'm not an expert, just saying what I've heard from a fellow in the US who restores old guns. Annealing would relieve the internal stresses produced by the welding process.
I bet that after all the work had been done, the value of the piece would be less than its as is value plus the cost of the work. Frame welded, stripped, rehardened, totally refinished. And some folks worry about preserving patina.



























