MPN: APAR505611


  • Caliber: 5.56 NATO
  • Finish: Type III Class 2 Hardcoat Anodized Finish
  • Upper Receiver: Aero Precision AR15 Upper Receiver
  • Handguard: Two-Piece USGI Style Polymer Handguard
  • M4 Feed Ramps: Yes
  • Muzzle Device: Mil-Spec A2 Flash Hider
  • Barrel: 20" 1:7 Twist 4150 Chrome Moly Vanadium Barrel
  • Muzzle Thread Pattern: 1/2"-28 TPI
  • Gas Block: Mil-Spec Front Sight Base (Pinned)
  • Gas Tube: Rifle-Length Gas Tube
  • Bolt Carrier Group: Not Included
  • Charging Handle: Not Included
  • Made in the USA

*This upper assembly does not come with Bolt Carrier Group and Charging Handle


  • Weight: ~4.43 lb.
  • Length: ~28.5"


  • AR-15 lower receivers


  • 1x Aero Precision 20" Rifle-Length 5.56 Complete Upper w/ Pinned FSB


These days, many civilians are looking to build modern and modular AR-15s with seamless handguards, M-LOK, shorter barrels, and a lot more. Though those builds look great too, some people still appreciate the original aesthetic of AR-15 or M16-style rifles. Moreover, with the simile designs that are adopted by the military, these rifles are also more affordable.

Where Aero Precision makes a lot of modern and modular upper receivers and assemblies for AR-15s, they also make the 20" Rifle-Length 5.56 Complete Upper, which has the same tried and tested design that can be seen on M16s.

Timeless Design

As far as aesthetics are concerned, the furniture and components on this upper assembly make it look similar to Military M16s. You get a standard USGI style two-piece polymer handguard in the front.

You also get a fixed front sight gas block, which is more durable than other options, and since it is fixed in place, it won't get damaged or move even after a lot of abuse. The front sight gas block on the Aero Precision upper also features a standard Bayonet Lug. For the rear sight, you get a standard M16 carry handle, with an aperture rear sight.

20-Inch Barrel

The Aero Precision 20-inch Upper has a full-length 20-inch barrel, which is great for accuracy and long-range with the 5.56 caliber. The barrel is made from 4150 Chrome Moly Vanadium, which is an alloy that is super strong and resistant to corrosion. The barrel has a 1:7 twist rate and a ½-28 thread pitch for muzzle devices. The barrel also comes equipped with a standard Mil-Spec A2 flash hider.

Mil-Spec Gas Block

Since this upper receiver is made to replicate a military rifle, it has a Mil-Spec gas block integrated into the front sight base. This makes the gas block more reliable and durable as well, perhaps at the cost of aesthetics. However, if the M16 aesthetic is what you are looking for, this type of gas block is perfect.

To complement the long 20-inch barrel, a rifle-length gas tube is used with the Aero Precision 20-inch upper receiver. The long gas tube results in a slower rate of fire and more reliable operation and feeding.

High-Quality Receiver

This upper assembly features a standard Mil-Spec upper receiver, which has a Type III Class 2 hardcoat anodized finish. It has a port door to prevent dust and debris from entering the chamber and also features a forward assist. To improve the reliability of the feeding mechanism, the receiver also has M4 feeding ramps.

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  • This Item: Aero Precision 20" Rifle-Length 5.56 Complete Upper w/ Pinned FSB
    MSRP: $565.00
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