Aero Precision M4E1 16″ 5.56 Complete Upper Receiver w/ ATLAS S-ONE Handguard – No Forward Assist

Original price was: $514.99.Current price is: $429.11.

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SKU: APAR712105M7

Product Description

This complete upper receiver features the same tried-and-true construction and aesthetics as Aero’s M4E1 Threaded Upper Receivers, without provisions for a forward assist. The included ATLAS S-ONE Handguard is designed with size and weight in mind. Featuring a trimmed-down top rail to help minimize weight and overall profile. Aero’s proprietary ATLAS attachment system is a durable and dependable mounting platform, maintaining a slim profile while still providing the strength and stability customers have grown to love from Aero Precision handguards.


  • M4E1 Threaded Upper Receiver, No Forward Assist.
  • 15″ ATLAS S-ONE Handguard.
  • 16″ 5.56 CMV Barrel.
  • Low Profile Gas Block and Mid-Length Gas Tube.
  • Port Door Assembly.
  • A2 Flash Hider.

M4E1 Threaded, No Forward Assist Upper Receiver Features:

  • No Forward Assist.
  • Custom enhanced forging that gives the upper receiver a “billet look” while maintaining the structural integrity of a forged part.
  • Picatinny profile that blends seamlessly with Aero’s Enhanced and ATLAS Series Handguards.
  • M4 Feedramps.
  • .250 takedown pin holes.

ATLAS S-ONE Handguard Features:

  • Front and rear Picatinny rail.
  • Eliminated center of top rail for weight reduction.
  • Indexing grooves in 12:00 position for positive grip control.
  • Quick disconnect sling socket at the 3, 6, and 9 o’clock positions.
  • 1.3″ Inside diameter.
  • 1.5″ Outside diameter.
  • Compatible with mil-spec AR15 upper receivers and barrels.
  • MLOK attachment points.

16″ 5.56 Barrel Features:

  • 5.56 NATO 16″ Barrel, 1/7 twist, 4150 CrMoV, QPQ, gas port drilled.
  • .750 gas block journal.
  • Mid-length gas system, .0785 gas port.
  • M4 Feed Ramp Extension.
  • HP and MPI tested.
  • Standard A2 flash hider.


This complete upper receiver does not include BCG or Charging Handle.




Technical Information

Color / Pattern

Firearm Compatibility


5.56 NATO / .223 Remington



Catalog Location

California Prop 65 Warning

WARNING: This product can expose you to chemicals, which are known to the State of California to cause Cancer and Reproductive Harm. For more information visit