Ever wondered if a detachable magazine could make or break the legendary Mossberg 590? We put the new 590RM to the ultimate test at Thunder Ranch, slamming it with 500 rounds of mixed 12 gauge ammo using just one double-stack mag. Joined by Clint Smith, Hop, Ivan from Kit Badger, and the TFBTV crew, we unleashed a no-holds-barred pump-action assault to see if this mag-fed evolution lives up to its rock-solid rep. Spoiler alert: things got messy. Check out our brutal reliability test to find out if the 590RM is a game-changer or a gimmick!