JP FULL MASS CARRIER LG FRAME SS W/ QPQ JP Full Mass Operating System Bolt Carrier Large-Frame (.308) Stainless Steel QPQ Black Finish Our full mass .308 carrier is designed to provide greater reliability in suppressed setups as well as SBRs and rifles without an adjustable gas system. Heavier than a standard DPMS LR-308 carrier, the JPBC-5 allows for the additional cycling delay required for reliable function in such setups. This design incorporates forward assist serrations, making it compatible with both DPMS and Armalite rifles. Each carrier also includes out Enhanced Gas Ring for more reliable function. Requires DPMS-pattern bolt, firing pin and cam pin. For a complete operating system, this carrier pairs best with the JPSCS2-10H2. Weight: 15.31 oz. with key installed.