Are you sure it's an M38 stock? If so it will have a relief in the barrel channel for the M38 rear sight base that is a sleeve around the barrel. Since M91/59s use the M91/30 rear sight base that fits on a dovetail without a sleeve there will be a gap on each side of the barrel are the rear sight. If there is no gap then it's a cut down M91/30 stock or a purpose made M91/59 stock.I just picked up a 91/59 in a post-war M44 stock yesterday over at Big 5. Got another one in a wartime M38 stock at the other Big 5 across town.