Reduced Power Spring For Sub-Sonic Loads
Specially-engineered spring is designed to optimize performance of AR-15s with 16" barrels chambered for .300 AAC Blackout and carbine-length gas systems. Specifically helps produce reliable function with sub-sonic ammunition. An effective and easy way to cure short cycling in under-gassed guns.
Big Book Catalog, Issue:68, Page:031
SPECS: 17-7 stainless steel.