Piston Kit – P Series Adjustable Micro Block




This system will work with .223/5.56 x 45 mm NATO. For other calibers, please contact Support.

Kit includes:

  • Patented One-Piece Bolt Carrier
  • P Series Micro Block – Adjustable (5 Settings – 100%/74%/53%/32%/11%)
  • Bolt Spring
  • Drive Rod with Bushing and Spring
  • Installation Instruction Card
  • Our Piston Kits No Longer Require the Receiver Bushing or Installation Dowel


The Adams Arms Piston System:

  • A short stroke free floating piston system.
  • Is Self-Cleaning.
  • Carbon and gases are expelled forward, away from operator.
  • Corrosive resistant coating processes.
  • Harmonics are not transferred into the barrel.
  • Doesn’t vent directly to atmospheric pressure; this eliminates flash signature and super sonic crack which is optimal for night vision and suppresses fire.
  • Has a Lifetime Warranty.


To select the correct length kit, use the following measurements:

  • Pistol: 4.846″ from barrel extension to shoulder
  • Carbine: 7.866″ from barrel extension to shoulder
  • Mid: 9.866″ from barrel extension to shoulder
  • Rifle: 13.241″ from barrel extension to shoulder
  • For 300BLK we only recommend a Pistol Gas Length and a Low Mass Carrier for optimal performance.

We recommend using a standard barrel nut or barrel nut with similar measurements for proper fit and function of the kit. Many aftermarket proprietary barrel nuts do not offer the clearance for the drive rod or proper seating of the spring and bushing.

Micro Gas Blocks should have the set screws torqued to 55-60 in-lbs

Installation Instructions: CLICK HERE

Additional Information

Weight 2 lbs
Dimensions 18 × 5 × 3 in
Adjustable Kit Length:

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Select Carrier:

Standard Carrier, Low Mass Carrier +$30.00

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