B5 Systems Sierra K AR-Platform Compact Collapsible Stock - OD Green - Sierra K Extension Kit Required

The B5 Systems Sierra K Stock is a purpose-built compact collapsible stock engineered for PDW (Personal Defense Weapon) and other small/compact weapon systems. Finished in OD Green, the Sierra K keeps overall size and weight to a minimum while delivering a stable, snag-free shooting platform.

The Sierra K features a reduced overall size with a slim cheek profile for a clean sight picture, paired with a snag-free adjustment lever for fast length-of-pull changes. Sling mounting is handled ambidextrously via a limited-rotation QD socket and integral fixed sling mounts, and an internal anti-slip butt pad keeps the stock planted under recoil.

The Sierra K is part of B5's compact weapon system and is intended to be paired with the Sierra K Extension Kit (sold separately) - a reduced-length, mil-spec diameter, 7075 aluminum, 5-position receiver extension paired with a short heavy buffer and extra-power spring. It is not compatible with a standard mil-spec receiver extension.

At just 6.6 oz and measuring 5.63" long x 1.5" wide x 3.8" tall, the Sierra K is a lightweight solution for AR-platform PDW builds, compact carbines, and other space-constrained setups.