U.S. Winchester Model 12, 12 ga. slide action shotgun.  Serial #970210, mfg. 1943.  Very good condition.  24” vent rib barrel has shiny bore.  2 ¾” chamber, choked CYL.  Fitted with Simmons round post rib and Cutts Compensator with Spreader tube.  Receiver stamped “US” with  Ordnance mark on right side.  Barrel has no serial numbers and has been re-blued – probably by Simmons during rib installation.  Target grade forearm has excellent finish and checkering.  Highly figured smooth butt stock has excellent finish with Pachmayr White Line recoil pad.  May have been  a civilian gun that was converted during the war to an aerial gunnery trainer, or a military riot gun (CYL choking), that was converted to a civilian skeet gun after the war.  Action works fine.  An interesting WWII M12 variation!  C&R OK.