Aero Precision M4E1 5.56 NATO 7.5″ ATLAS R-ONE Complete Upper


Fully Assembled and Warrantied by Aero Precision

Aero Precision M4E1 5.56 NATO 7.5" ATLAS R-ONE Complete Upper

Available in Black or FDE

Aero Precision M4E1 5.56 NATO 7.5" ATLAS R-ONE Complete Upper is the most efficient way to assemble your own custom firearm; fully assembled and warrantied by Aero Precision. The R-ONE handguards are designed with size and weight in mind, providing the perfect addition to your lightweight build. Aero Precision'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.

*NFA Rules apply!
**The muzzle device is NOT pinned nor welded to the barrel.
***Does not include Bolt Carrier Group or Charging Handle.

M4E1 Threaded Upper Receiver Features:

  • New enhanced forging that gives the upper receiver a "billet look"
  • M4 Feed ramps
  • .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

7.5" 5.56 Pistol Length Barrel Features:

  • Material:  Chrome Moly Vanadium
  • Finish: QPQ Corrosion resistant finish both inside and out.
  • Gas System: Pistol Gas w/ .750 Journal
  • Weight: 17.25oz
  • Other: M4 Extension | HP and MPI Tested
  • Standard A2 flash hider

Also available with the ATLAS S-ONE Handguards


  • M4E1 Threaded Assembled Upper Receiver
  • M-LOK ATLAS R-ONE Handguard
  • 10.5" or 16" 5.56 CMV Barrel
  • Low Profile Gas Block and 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.
SKU APAR700701M0 (BLK) | APAR700711M0 (FDE)
Manufacturer Aero Precision
Made in America Yes
Assembled Yes
Receiver M4E1 Threaded; M4 Feed Ramps
Barrel 5.56 NATO; 7.5" w/ A2 Birdcage Flash Hider
Handguard Free Float; MLOK; ATLAS R-ONE; 7"
Platform AR15
Finish Black Anodize | Flat Dark Earth Cerakote
Gas System Pistol; .750 Diameter

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Weight N/A
Dimensions N/A
Barrel Length


Gas System


Gas Block Diameter


Muzzle Thread

1/2 x 28


5.56 NATO


Black, FDE

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