The Mil-Spec AR-15 Carbine Buffer Spring is made in the USA. This AR-15 buffer spring for sale is for adjustable AR15/M4 Carbine stock mil-spec buffer tubes. A Mil-Spec AR-15 Carbine Buffer Spring is the right choice for a new build, maintenance, or upgrade of your AR-15. The carbine buffer spring is made to M4A1 Mil-Spec specifications. This AR-15 carbine buffer spring length is a direct drop-in replacement for AR-15/M4 carbine models and AR Variants. This high-quality M4 AR-15 carbine buffer action spring fits all mil-spec and commercial carbine receiver extension buffer tube assemblies. By upgrading your worn-out AR-15 carbine action spring to a new one, you will provide the extra power your AR-15 or M4 carbine rifle needs to cycle properly if your old one has weakened and failed. Limited lifetime warranty.