Magazine tube nut for attaching Nordic Components extensions. Manufactured from aluminum billet and anodized matte black.
Click this link to find the extension tube for your firearm: Extension Tube
Big Book Catalog, Issue:71, Page:205
Barrel Magazine Clamp (BMC) - Clamps to the barrel and the extended mag tube. Stabilizes and supports the tube; includes built-in sling swivel stud. Benelli 3-round and Remington 5-round magazine extensions include barrel magazine clamp.
Big Book Catalog, Issue:71, Page:206
SPECS: BMC-R Clamp - Fits Benelli Nova/Super Nova/M4, Rem. 870, and Win. 1200/1300 Def. BMC-U Clamp - Fits Rem. 1100/11-87.