JP VMOS Bolt Carrier Small Frame - 5.56mm

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MSRP $306.00 $291.00

In stock

  • Product Description

    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.


    • Enhanced tunability of operating system
    • Guaranteed reliability of difficult configurations
    • Overcomes all fouling build-up
    • 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
    • Additional forward assist serrations for one full inch of travel


    • 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 the 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.

    More Information
    Manufacturer JP Enterprises
    AR-15 Parts Bolt Carriers
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