Several gun companies got into using steel flat, then rolling or pressing/forming, and welding. The 24 and 37 Winchester shotguns frames were made that way. There were two designs for the 37 frame, where one had a top stamped section, with flange, welded on at the water table on each side, and another that folded completely over, with a welded seam at the top, with a tang added at the back. Both designs had round breech blocks brazed into slots that were pre-machined into the flat, after they bent it up. The steel-built idea was a good one, for an economy gun.
However, I have ran into two 37s, that had porosity in the welds, which was uncovered during polishing, that had to be ground out, then rewelded, to save the frame. One had porosity the full length of both welds, on each side. Those were most likely stick or gas welded, I would assume, as MIG didn't come out until around 1950. They may have been later guns, though, as the last were made in 1963, and some were made at Cooey, if I recall. Since there are no serial numbers, it is up for guess as to what caused it when. The only way to guess, would be by the era they were made, using the two patents as a guide. Neither were red letter, nor had the pig tail lever.
