The JP Low Mass Carrier works out nicely in the new type of civilian machined receivers that don't have a forward assist. Although it doesn't have the forward assist serrations, it functions in military type receivers as well. It just won't allow the use of forward assist on the receiver. The dust cover functions normally.
You may be wondering why some of the stainless carriers appear black. This is due to a new state of the art surface finish for stainless called QPQ (Quench, Polish, Quench). This is a five-step process resulting in a rock hard surface with natural lubricity. Some want the bright polished look and that is available on the JPBC-3 Low Mass carrier, but not the JPBC-2 tactical carrier.
The JP LRP-07 has our large format AR-10 type Low Mass carrier. The JPBC-4 AR-10 low mass stainless bolt carrier is also finished in black QPQ hard coat for superior wear and natural lubricity. The JPBC-4 will also improve the sight recovery on the DPMS LR-308 or the Armalite AR10. However, it must be used with a DPMS LR-308 bolt assembly, firing pin, cam pin and firing pin retainer.
Do not attempt to use the JPBC-4 with the Armalite bolt assembly, firing pin or cam pin. Unlike the AR-15/M16 platform on which just about everything is cross compatible, each AR-10 type rifle such as the JP LRP-07, DPMS LR-308, Armalite AR-10, Knights SR-25 or Rock River AR-10 is inherently different with only limited cross compatibility of components. Always check compatibility anytime you order aftermarket accessories for AR-10 type rifles.
JP Full Mass Bolt Carriers
For police tactical duty or any application where absolute reliability is the main criteria, use the FMOS™ or Full Mass Operating System with 416 stainless steel special design carrier that includes forward assist serrations and a dust cover notch. The bore of the JP stainless carriers has a roller burnished finish for frictionless operation with no chance of peeling chrome as in standard mil-spec carriers. The exterior bearing surfaces are hand polished. When properly lubricated, both systems make your rifle feel like it was cycling on ball bearings.
Both the JPBC-2 and the JPBC-3 feature a 100% increase in bearing surface for smoother operation and improved alignment and lower wear in the upper receiver. Both are M15 semi auto configuration in the rear with the mil-spec longer cocking pad in the front for best reliability. This is hands-down the best designed and highest quality general purpose carrier on the market. Sold as carrier with installed key.