Does NOT have forward assist serrations but does feature dust cover notch. 100% increase in bearing surface for smoother operation, improved alignment and lower wear in the upper receiver. Recommended for competition and recreational use. Finished with a Quench-Polish-Quench (QPQ) hardcoat process to yield incredibly hard and lubricious bearing surfaces. Reliability with these parts is excellent for competition and recreational use. Most shooters that use and maintain this operating system feel that it is a great performance improvement. JP .308 High Pressure Enhanced Bolt
For anyone using .308/7.62 AR-type rifles, it is common knowledge that many factory rounds exhibit excessive primer flow and/or ejector smear. At its core, this is a result of ammo development being done by manufacturers only for manual platforms without testing in semi-auto platforms. Some rifle manuals even record the maximum recommended load data beyond the functional range of these rifles. Unfortunately, these issues will persist until the manufacturers of ammunition realize that an AR platform requires a unique pressure curve to allow for both accuracy and reliability.
Manufactured to the exacting standards of our standard bolt offerings, the High Pressure EnhancedBolt™ design represents a giant leap forward in alleviating the problems traceable to over-pressured loads—namely primer flow, ejector smear, extraction issues, and ignition reliability. In combating these problems, this new bolt design opens up a much broader range of ammunition compatibility and load density in the AR .308/7.62 and other variants such as 6.5mm or 6mm calibers in this platform.
The critical advancement of this bolt comes in the reduced diameter firing pin orifice that precisely accommodates the .062" tip of our proprietary low mass firing pin. This modified relationship virtually eliminates primer flow and the possibility of pierced primers on any SAAMI or NATO specification ammunition while the reduced mass of the firing pin also improves lock time and ignition reliability with hard primers due to the concentration of kinetic energy on a smaller impact area. This is especially advantageous with some aftermarket match-type fire control systems that may use reduced-power hammer springs.
Among its other enhancements, the .308HP bolt features an improved ejector pin hole and modified ejector to mitigate case head extrusion and frequent brass shavings. The JP Enhanced Extractor eliminates virtually all extractor-related failures while the JP Enhanced Gas Rings provide a more reliable, lower friction gas seal with longer lifespan.
While ultimately every end user needs to be aware of the ammunition limitations of their large-frame AR, the JP .308HP bolt offers multiple advancements to vastly increase the ammunition and operational abilities of the platform.
WARNING / Disclaimer: The JP .308HP bolt does not allow for the use of excessive pressure, overloaded ammunition that exceeds SAAMI specifications. When evaluating new ammunition, always start on the low- to mid-range of any published load data and work up. A good indicator of working pressure is the primer retention on the subsequent loading of a case. A noticeable loss of primer pocket tension indicates that your ammunition has excessive pressure and has overworked the case.
BC-4 Bolt Carrier Assembly Group AR-10 Compatibility
This notice pertains to any rifle based on the large-format AR-10-type or LR-308 platform typically chambered in .308 Winchester, 7.62x51 NATO or other cartridges requiring the longer magazine format.
Be aware that these receiver platforms are not standardized like the AR-15/M16 platform for which most parts are cross-compatible. Before ordering accessories and parts for your large-format rifle, make sure the parts are compatible with your particular platform. The JPBC-4AHP complete bolt carrier assembly and its parts are compatible with the DPMS family of AR-10 products.
NOTICE: With the Armalite/Rock River family of large-frame receivers, this assembly can only be used as a complete bolt carrier assembly group. Interchanging individual components will result in an unsafe configuration. DO NOT under any circumstances mix and match components between the platforms. Only use the complete JP bolt carrier assembly in the Armalite/Rock River platforms.