Aero Precision M4E1 10.5″ 5.56 Complete Upper Receiver w/ ATLAS S-ONE Handguard

Original price was: $459.99.Current price is: $409.99.


Product Description

This complete upper includes Aero’s new ATLAS S-ONE Handguard. The S-ONE line of handguards is designed with size and weight in mind, providing the perfect addition to your lightweight build. 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.
  • 9.2″ ATLAS S-ONE Handguard.
  • 10.5″ 5.56 CMV Barrel.
  • Low Profile Gas Block and Carbine Length Gas Tube.
  • Product comes assembled
  • This complete upper does not include BCG or Charging Handle.
  • The muzzle brake that comes with this complete upper receiver is NOT pinned nor welded to this barrel.

M4E1 Threaded, No Forward Assist Upper Receiver Features:

  • No Forward Assist
  • New enhanced forging that gives the upper receiver a “billet look”
  • New picatinny profile that blends seamlessly with our Enhanced Series Handguards
  • M4 Feedramps
  • Laser engraved T-marks
  • Includes port door and forward assist installed
  • .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
  • Compatible with low profile gas blocks
  • 1.3” Inside diameter
  • 1.5” Outside diameter
  • Compatible with mil-spec AR15 upper receivers and barrels

10.5″ 5.56 Barrel Features:

  • 5.56 NATO 10.5″ Barrel, 1/7 twist, 4150 CrMoV, QPQ, gas port drilled.
  • .750 gas block journal.
  • Carbine 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



Firearm Compatibility


5.56 NATO / .223 Remington

Barrel Twist




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