From BCM: MK2 MOD 1 buffer series is to ONLY be used on the AR15 receiver platform, and it ONLY works with the BCM MK2 Receiver Extension (BCM part #BCM-MK2-RE) and the Mil-Spec Rifle M16 Action Spring. Using any component not specifically designed for the MK2 MOD1 Intermediate Buffer can damage the weapon and possibly injure the operator.
Uses an M16A4 rifle spring with more coils than an M4 carbine, increasing consistency and expanding the operating range.
Provides a more consistent carrier velocity, improving accuracy and reliability compared to conventional carbine buffer systems.
Increased internal counterweight travel decreases bolt bounce
