Adams Arms AR-15 P2 Adjustable Gas Piston Pistol Upper Receiver Assembly 5.56x45mm NATO 11.5” Barrel


Category: Product ID: 13200


This Adams Arms P2 Adjustable Gas Piston Upper Assembly is chambered in 5.56x45mm NATO and comes ready to fire right out of the box after installation onto any standard AR-15 pistol or registered SBR lower receiver.  The P2 features a melonite finished, 11.5″ barrel with a 1 in 7″ twist, making it capable of stabilizing medium- to heavy-weight projectiles of up to 77 grains. The P2 configuration comes equipped with a free floating, Adams Arms M-LOK handguard. The low profile P-series Micro gas block is 40% lighter than previous railed versions and fits nicely under the rail. Together, the forged A3 flat-top upper and handguard create a long, uninterrupted top rail interface with ample room for mounting optics and/or iron sights.

The upper’s barrel has been finished inside and out with Adams Arms’ proprietary QPQ Melonite treatment that bonds with the metal on a molecular level. Also referred to as salt bath nitriding, this treatment produces an extremely hard, slick surface on steel that resists carbon adhesion and increases corrosion resistance, extending a barrel’s service life by reducing the friction produced inside the bore upon firing for a net decrease in bore surface wear over time. Nitriding converts the barrel steel’s surface without any build-up, retaining all of the benefits of traditional chrome lining without suffering the accuracy degradation commonly encountered due to uneven application of chrome inside the barrel’s bore. The end result is a barrel that’s capable of producing accuracy on par with a match stainless steel tube, while also exhibiting the longevity and resilience of a chrome lined, mil-spec barrel.

All Adams Arms uppers feature a short stroke gas piston operating system, which prevents hot gas and debris from being directed back into the action upon firing. The result is a rifle that runs cooler, cleaner and more reliably than those utilizing a standard direct gas impingement system of operation. To ensure that damage doesn’t occur to the buffer tube from carrier tilt, the bolt carrier is equipped with enlarged “skis” to help guide it into the receiver extension. The bolt carrier’s solid steel, 1-piece construction incorporates an integral piston strike face to guarantee integrity over time, while the bolt assembly is spring loaded for proper lock-up and to help reduce bolt bounce and cam pin wear. All piston components are finished in QPQ Melonite for corrosion resistance and easy cleaning/maintenance.


  • Free float M-LOK handguard
  • Extended A2 flash hider
  • P-Series Adjustable Micro gas block
  • Short stroke gas piston
  • Ambidextrous Charging Handle
  • Short stroke free floating piston system
  • Self-cleaning and corrosive resistant piston coating
  • Carbon and gases are expelled forward
  • Product Information

    Cartridge 5.56x45mm NATO
    Material Aluminum
    Barrel Length 11.5 Inches
    Twist 1:7 Inches
    Threads 1/2″-28
    Sights No
    Gas System Length Carbine
    M4 Feed Ramps Yes
    Upper Receiver Type A3 Flat-Top
    Barrel Material 4150 Chrome Moly Vanadium Steel
    Handguard Free Float M-LOK
    Mil-Spec or Commercial Mil-Spec
    Country of Origin United States of America
    Compatible With

    Delivery Information

    Shipping Weight 4.835 Pounds


There are no reviews yet.

Be the first to review “Adams Arms AR-15 P2 Adjustable Gas Piston Pistol Upper Receiver Assembly 5.56x45mm NATO 11.5” Barrel”

Your email address will not be published. Required fields are marked *

Stay Connected


Tacticoolammoshop offers the most popular calibers of ammunition from 9mm to .223 as well as brands that you trust - like Federal and Winchester - because you deserve the best! Our convenient site navigation and "blitzkrieg shipping" ensure your ammo shopping experience is a great one.
In addition to offering a wide variety of handgun rounds, rifle ammo, and shotgun shells for sale, we also frequently stock great deals on ammo cans and other accessories. So if you're looking for a great ammunition selection, you've found it!

Company Info

Get in touch

+1985 467 9151
82 12th Street, Office 14, LA

TACTICOOL AMMO SHOP2024. All Rights Reserved.