B5 Systems Sierra K Receiver Extension Kit, Black

Description

The B5 Systems Sierra K Receiver Extension Kit provides the proprietary mounting system for the Sierra K buttstock. The kit uses a reduced-length, mil-spec diameter, 7075 aluminum, 5-position receiver extension and is finished in black. All parts are made to mil-spec materials and finishes and are manufactured in the USA.

Key Specifications

• The assembly is a Buffer Tube Complete Assembly.
• Designed for the Sierra K model.
• Finished in Black.
• The receiver extension is a 7075 aluminum, reduced-length, mil-spec diameter, 5-position extension.
• The kit includes a short heavy buffer (3.5 oz).
• The kit includes an extra power spring.
• The kit includes a castle nut.
• The kit includes a quick disconnect end plate.
• The listed weight for the kit is 3.50 oz.
• Built with mil-spec materials and finishes and Made in the USA.

Compact and built to mil-spec standards, the Sierra K Receiver Extension Kit supplies the hardware needed to mount the Sierra K buttstock while maintaining a conservative, five-position receiver extension. Components are focused on durability and straightforward function—ideal for users who prioritize reliable, proven features and a clean, black finish in their AR accessory setup.