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JP VMOS™ Carrier Group with JP EnhancedBolt
   .223 | 6.5G | 6.8 SPC II | .224 Valkyrie
   Stainless Steel
   QPQ Black Finish

Cycling problems? The VMOS™ brings the discipline your rifle needs.

For difficult setups like suppressed rifles and exotic caliber chamberings, some degree of mass regulation is required for optimal performance. This is especially true in the absence of an adjustable gas block. Residual gas and excessive fouling can grind your rifle to a stop.

One size never fits all when it comes to gas-operated rifles. The Variable Mass Operating System (VMOS™) carrier ensures reliability through additional reciprocating mass but provides more custom tunability. Combined with our Silent Captured Spring, multiple masses are exchangeable to perfectly tune your operating system weight.

The EnhancedBolt™ is compatible with any AR-15 platform using a Mil-spec bolt carrier and sub-components.

Package includes carrier, bolt assembly, cam pin, firing pin, firing pin retainer pin and instruction sheet.

Weight: 12.8 oz.

Features (bolt carrier):

  • Enhanced tunability of operating system
  • Guaranteed reliability of difficult configurations
  • Overcomes heavy fouling build-up
  • Near complete elimination of bolt bounce
  • Roller-burnished bore for frictionless operation
  • Rock-hard QPQ finish provides remarkable natural lubricity
  • Extremely smooth cycling with proper lubrication
  • Increased bearing surfaces for slower wear and longer component life
  • Longer cocking pad for optimal reliability

Features (bolt):

  • SAE 9310 steel construction for superior resiliency and extended lifespan
  • DLC coating provides extreme surface hardness and lubricity while maintaining a ductile core
  • Near frictionless surface finish
  • Fully compatible with Mil-spec sub-components
  • Increased diameter cam pin hole eliminates most common bolt breakages
  • Improved lug geometry for reduced wear and easier locking/unlocking
  • Enhanced Ejector mitigates head case extrusions and reduces brass smear
  • Enhanced Extractor optimizes extraction function and eliminates common ejection failures
  • Enhanced Gas Ring reduces internal friction and carrier wear while maintaining near indefinite gas seal


  • VMOS™ carriers use the same steel and tungsten weights as GEN 2 Silent Captured Spring units. Only the forward mass is reconfigurable. The rear steel mass cannot be exchanged.
  • This carrier will not cycle with a standard buffer retainer plunger installed and should be used only with a Silent Captured Spring.
  • Because our Law Tactical Folder Silent Captured Springs require use of a buffer retainer plunger to work, they are also not compatible with this VMOS™ bolt carrier.

  • The JPBC-6 bolt carrier is full-auto capable when used in conjunction with other select-fire components. All NFA rules apply.


Patents: 10,184,739

Bolt Assembly:

Price: $455.00