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Aero Precision M4E1 5.56 Partial Upper Receiver w/ Atlas R-One Handguard - 14.5" Carbine Length Black

AR-15 Partial Upper Receiver

Out of stock

Aero Precision M4E1 5.56 Complete Upper Receiver w/ Atlas R-One Handguard - 14.5" Carbine Length Black


This complete upper includes Aero Precisions new ATLAS R-ONE Handguard! The R-ONE handguards are designed with size and weight in mind, while still providing plenty of real-estate to accommodate any attachment needs the end user may have. 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 Assembled Upper Receiver
  • ATLAS R-ONE Handguard of choice
  • 14.5" 5.56 M4 CMV Barrel, Carbine Length
  • Low Profile Gas Block and Mid Length Gas Tube
  • Product comes assembled
  • This complete upper does not include BCG or Charging Handle. These products may be selected as add-ons
  • under the FINISH YOUR BUILD tab
  • The muzzle brake that comes with this complete upper receiver is NOT pinned nor welded to this barrel. Per the National Firearms Act, the muzzle brake MUST be pinned and welded to achieve the necessary 16" as defined by the ATF for a rifle build.


M4E1 Threaded Upper Receiver Features:

  • New enhanced forging that gives the upper receiver a "billet look"
  • New picatinny profile that blends seamlessly with our Enhanced Series Handguards
  • M4 Feedramps
  • .250 takedown pin holes
  • Laser engraved T-marks
  • Includes port door and forward assist installed


ATLAS R-ONE Handguard Features:

  • Full top picatinny rail for optional attachments
  • 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
  • Learn More about our NEW ATLAS Handguards


14.5" 5.56 M4 CMV Barrel, Carbine Length Features:

  • Chamber: 5.56
  • Length: 14.5"
  • Twist: 1 in 7
  • Threading: 1/2"x28
  • Material: Chrome Moly Vanadium
  • Finish: QPQ corrosion resistant finish both inside and out
  • Gas Block: .750
  • Gas Port: .0785
  • Gas System Length: Carbine
  • Weight: 25.28 oz
  • M4 Barrel Extension
  • HP and MPI Tested



  • Platform: AR15
  • Series: Atlas
  • Caliber: 5.56 NATO
  • Barrel Length: 14.5"
More Information
SKU APAR700704M32
Product Type AR-15 Partial Upper Receiver
Manufacturer Aero Precision
Gas Block Diameter .750"
Thread Pitch 1/2x28
Inside Diameter 1.3"
Color Black
Gas Length Carbine
Rail Length 12"
Barrel Length 14.5"
Caliber 5.56 NATO