Pardon my neophyte terminology here, please. Rather than trying to shim the hook on my project gun, I was considering welding it up and then filing and fitting to take up the looseness in the barrel/breech fit. I've done this successfully on an old set of barrels that were beyond any hope. I used my Mig welder on it. I have Mig, Oxy/Acetelene and Stick welders, but no Tig. Wish I had the Tig, but I cannot afford it right now. Any problems with using the Mig? Any suggestions?