MPN: FGAA-03203 / FGAA-03206 / FGAA-03217 / FGAA-03220


  • Short stroke free floating piston system
  • Carbon and gases are expelled forward, away from operator
  • LifeCoat finish for surface protection, lubricity, and hardness
  • Harmonics are not transferred into the barrel
  • 5 adjustable gas setting - 100%/74%/53%/32%/11%
  • Doesn’t vent directly to atmospheric pressure; this eliminates flash signature and super sonic crack which is optimal for night vision and suppresses fire
  • Newest version - this piston kit no longer require the receiver bushing or installation dowel

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

Micro Adjustable Block Adjustment Diagram


  • Material: Proprietary 8620 Steel
  • Finish: LifeCoat
  • Gas Adjustment: 5 Positions (100%/74%/53%/32%/11%)
  • Piston Gas Block Weight: 3.81 oz.
  • Bolt Carrier Weight: 9.45 oz.


  • Most .223/5.56 x 45 mm NATO AR-15 with .750" gas seat

*These piston systems are designed for .223 and 5.56, and might not be compatible with other calibers.

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

*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.


  • 1x Adams Arms P Series Adjustable Micro Block
  • 1x Adams Arms Patented One-Piece Bolt Carrier
  • 1x Bolt Spring
  • 1x Drive Rod with Bushing and Spring

*Does not come with bolt assemble, firing pin, and cam pin.


The Adams Arms P Series Adjustable Micro Block Piston Kit converts your AR-15 into a short stroke piston-driven rifle, eliminating the downsides of direct impingement. The system is designed to vent the gases forward instead of onto the bolt; this dramatically reduces the amount of time you must spend cleaning your weapon.

The included P Series Adjustable Micro Block gives you the ability to adjust the gas level for three main types of shooting: standard, suppressed, or single shot. As the short stroke system momentarily delays the release of the gases, the noise and flash signature are reduced, making this conversion kit perfect for users of suppressors. The metal parts of this kit are given a corrosion-resistant coating.

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