CAA “CBST” Carbine Buffer Tube Spring

Mil-spec recoil spring designed for the 6-position collapsible stocks supplied in CAA’s CBST stock assemblies. It is a standard power carbine spring that matches U.S. M4 technical data.

The spring drops into any mil-spec 6-position receiver extension. Replace tired or mystery springs every 5–7k rounds to cure short-stroking, weak ejection or failure to lock back.