I have here a WW2 riot sg with matching #'s. Just out of curiosity I removed the butt stock and found another set of #'s. They do not match the receiver/barrel ser#'s. This sg did go through an arsenal after the war. Has anyone seen this before., 1st two pics are of the "riot sg" in question, the 3rd pic is a M97 trench sg of the same vintage.