I had flame cutting on the underside of the top strap of my 1970's vintage Smith and Wesson Model 28 that I bought used. The gun had a leaded up barrel and had obviously seen some use by the previous owner, after a good cleaning it served me well. I had the gun for almost 20 years and primarily shot .38 specials through it, although it also had a few hundred rounds of .357 magnum passed through the bore.
I minor cut was only visible when I gave a good cleaning on the frame. I think it would have taken quite alot of shooting before the cut would have become a problem. I have also seen flame cutting on 1940's vintage Smith and Wesson military revolvers, many of those seen at gun shows look really trashed, shame, as I would like to add a WW 2 Smith to my collection, but not an abused one! :shock: