The B5 Systems Sierra K Extension Kit in Black is a streamlined, minimalist stock solution for AR-15 platforms, designed to provide a low-profile alternative to traditional buffer tube and stock assemblies. This kit integrates the Sierra K polymer receiver extension with a compact, fixed buttstock profile, making it ideal for lightweight builds, PDW-style configurations, or law enforcement and defensive carbines. Built for maximum durability and ease of use, the kit offers compatibility with standard AR-15 lower receivers and buffer systems.
Constructed from reinforced high-strength polymer, the Sierra K extension is durable yet lightweight, with an internal rib structure for added rigidity. The fixed length and slim profile help reduce snag hazards and weight while maintaining a secure shoulder weld for stable shooting. Finished in classic matte black, this kit delivers a clean, tactical look and pairs seamlessly with other B5 Systems components like the P-Grip and handguards.
B5 Systems Sierra K Extension Kit Specifications
Manufacturer: B5 Systems
Model: Sierra K Extension Kit
Fit: AR-15
Color: Black
Material: Reinforced high-strength polymer
Type: Fixed stock/receiver extension hybrid
Compatibility: AR-15 lower receivers
Application: Minimalist and compact rifle/pistol builds
More Information
Condition
New in Box
Finish Per Color
Black
Manufacturer
B5 Systems
Manufacturer Part Number
SRK-1660
Model
Sierra K Extension Kit
Type
Buffer Tubes
UPC
814927024793
WARNING: This product can expose you to chemicals including arsenic, which is known to the State of California to cause cancer. For more information, go to WWW.P65WARNINGS.CA.GOV
Questions And Answers
Reviews
Due to increased state legislation around firearms, you must be 18 to access our site.
