Upgrade your AR15, M16, or M4 with the BCM MK2 Receiver Extension. Crafted from durable 7075T6 aluminum, this Mil-Spec buffer tube is designed to meet stringent military specifications. Its unique design features a slightly smaller dimension for stock fitting, ensuring optimal performance. Please note that this receiver extension requires a rifle action spring and specific BCM MK2 buffer; carbine and rifle buffers are incompatible. Enhance your firearm’s reliability and functionality with this premium receiver extension from Bravo Company Mfg.