BCM MK2 RECEIVER EXTENSION

Description

The BCM MK2 Receiver Extension is the foundation of BCM’s MK2 Recoil Management System, and it exists to solve a specific problem with conventional carbine buffer arrangements. Standard carbine buffer tubes limit the travel distance available to the buffer, which in turn constrains how the bolt carrier’s rearward energy can be managed. The MK2 tube uses an intermediate length — longer than a standard carbine tube but shorter than a full rifle tube — that creates additional buffer travel. That extra travel lets the system slow the carrier more gradually, reducing the sharp, abrupt recoil pulse that carbine-length systems can produce.

Because this geometry is purpose-built, the MK2 tube is not a drop-in replacement for a conventional carbine setup. It requires the BCM MK2 buffer and a standard M16 rifle action spring — the longer spring provides more coils and a more consistent force curve than a carbine spring, which widens the operating envelope across varying ammunition and suppressor configurations. Carbine and rifle buffers will not function correctly here.

The tube itself is machined from 7075-T6 aluminum and finished with a Type III Class 2 hard coat anodize per Mil-A-8625F, giving it the same surface hardness specified for military components. Dimensions conform to mil-spec, so it accepts stocks built to that standard — including USGI, Colt, LMT, SOPMOD, and VLTOR designs. It is also compatible with most AR-10 lower receivers, which broadens its usefulness beyond the AR-15 platform. If you are already running BCM’s MK2 buffer or planning to build around the system, this tube is the required starting point.