Thanks for all the responses.
Barrel came out great, had to turn it in about 50-60 degrees, which was 8 or 9 thou. Didn't want to file the frame and setup in the mill would have been a pain so I elected to put the barrel in the lathe and push the shoulder back on that. Forcing cone gap came out...
Hello, all
Came up with an M&P Serial # 810XXX putting it 1940-1945 according to my S&W book. Barrel had been cut off 2-1/2" - 3", star stamped on butt before serial number so I assume S&W cut the barrel but who knows. Also SV stamped. Book says these were stamped V. Barrel had a couple rounds...