B5 Systems Sierra K Stock Black AR-15 LR-308

The B5 Systems Sierra K is a compact stock for AR-15 platform rifles, designed for use on PDW and other compact weapon systems. Its reduced overall size and slim cheek profile are meant to keep the firearm short and manageable in tight spaces.

The stock uses a low-profile adjustment latch that is designed to be snag-free, along with a slim ergonomic cheek weld, a limited rotation quick-detach mount, and integral fixed sling mounts that are ambidextrous. Internal tensioners and an anti-slip buttpad are included, and the hardware is color-matched steel.

The Sierra K mounts to a shortened compact Mil-Spec receiver extension, which is sold separately. It is not for standard-length buffer tubes, and installing it on one will prevent the stock from fully collapsing.

• Platform: AR-15
• Brand: B5 Systems
• Model: Sierra K
• Color: Black
• Fits: Compact Mil-Spec receiver extension (sold separately)
• Not compatible with: Standard-length buffer tubes
• Mounts: Ambidextrous fixed sling mounts and limited rotation QD mounts