Your gun is a Sweet Sixteen Auto-5 Shotgun. It was made in 1957. Value depends on condition. Used with less than 85% finish would start at around $400 and go over $1500+ for near new condition or mint. Percentage of finish is not the only factor in used A-5's. Recoil pads and poly chokes decrease value. Uneven bluing wear or sharp gouges, cracked forearms, all play a role. The best senario is to have a gun shop appraise the gun. Thank you for asking the question.