Mossberg SA-20, Semi-automatic, 20Ga 3, 26 Barrel, Blue Finish, Walnut Stock, Right Hand, 5 Choke Tubes - F,IM,M,IC,C, 4Rd 75789 The Mossberg SA-20 is a lightweight, soft shooting 20 gauge sporting shotgun that is perfect for both hunting and target shooting. The SA-20 has a smooth cycling semi-automatic gas operated system.