I agree with Cayugad and Nchawkeye.
I have revived many very neglected and left for useless or dead ML's to either excellent or acceptableshooting condition. Onlyin a couple of instances have a come across an ML that I ended up plugging the bore so could not be fired. The reason was not so much the rust/pitting, but because the barrels were bulged from double loading (loading another charged load on top of load already in the bore = big no no!).

Tahquamenon