There is no doubt that Oscar Frederick Mossberg’s 12-ga., pump-action Model 500 shotgun is a proven design—serving defensive roles both in private homes and the on the battlefield since its inception in 1960. The Model 500 has seen changes over the decades, varied and customized for myriad roles and pursuits, but this week’s feature gun is a collaboration between two companies. The Model 500 ATI Scorpion arrives from the factory configured with heat shield, collapsible stock and rail for optics. Advanced Technology International (ATI) has been a premier manufacturer of accessories for the 500 platform, and it only makes sense these two companies would unite. You can learn more in this week's NRA Gun of the Week video hosted by American Rifleman's Christopher Olsen.