The B5 Systems Sierra K Receiver Extension Kit is the proprietary mounting system designed specifically for the Sierra K Buttstock. It includes a reduced-length, mil-spec-diameter 7075 aluminum 5-position receiver extension, a short, heavy buffer (3.5 oz), an extra-power spring, a castle nut, and a quick-disconnect end plate. All components are made of mil-spec materials and finishes for reliable performance.
Features
- Complete proprietary mounting kit for the Sierra K Buttstock
- Reduced-length 7075 aluminum mil-spec diameter 5-position receiver extension
- Short heavy buffer (3.5 oz)
- Extra power spring
- Castle nut and quick disconnect end plate
- Mil-spec materials and finishes
- Made in the USA
