Whether starting a new rifle build or upgrading an existing one the BCM MK2 recoil mitigation system offers less felt recoil while maintaining and improving reliability. Comes as a complete kit ready to mount on any AR pattern rifle.Features :3.8oz buffer weight offers Increased internal counterweight travel to reduce bolt bounceInternal spring to reduce noise of counter weight shifting and ensure more consistent weight placementMil-Spec M16A4 rifle spring with more spring coils than M4 carbine, increases consistency and widens operating envelope8 Position buffer tube for extended adjustability