The Nordic Components standard shotgun barrel clamp provides extra rigidity for your magazine extension. Each clamp half has a centrally-located 10-32 threaded hole to accept accessories” such as a sling stud” barrel clamp tac rail or QD sling mount. Designed for Nordic extension tubes (1.060″ diameter).
Nordic Components Shotgun Barrel Clamp, Designed for 12GA MXT Extensions, Compatible with Most 12GA Shotguns, Features 10-32 Threaded Hole On Each Side for Mounting Accessories and Rails, Not Compatible with Mossbergs, Benelli Nova/Super Nova BCL-12
