Aero Precision 5.56 NATO M4E1 ATLAS S-ONE Complete Upper


Fully Assembled and Warrantied by Aero Precision
SKU: M4E1-CU-ATLAS-S Categories: , , Tags: ,

Aero Precision 5.56 NATO M4E1 ATLAS S-ONE Complete Upper

Available in 10.5″ Carbine or 16″ Mid-Length

Aero Precision 5.56 NATO M4E1 ATLAS S-ONE Complete Upper is the most efficient way to assemble your own custom firearm; fully assembled and warrantied by Aero Precision.  The S-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 for the 10.5″ barreled model.
**The muzzle devices are 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 Feedramps
  • .250 takedown pin holes
  • Laser engraved T-marks
  • Includes port door and forward assist installed

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

5.56 Barrel Features:

  • Select between a 10.5″ Carbine or 16″ Mid-Length barrel
  • 5.56 NATO 1/7 twist, 4150 CrMoV, QPQ, gas port drilled
  • .750 gas block journal
  • Carbine length gas system (10.5″) | Mid-Length Gas (16″)
  • .0785 gas port
  • M4 Feed Ramp Extension
  • HP and MPI tested
  • Standard A2 flash hider

Choose between 2 Configurations:

APAR700302M2 / APAR700312M2 – 10.5″ Carbine w/ 9″ ATLAS S-ONE MLOK
APAR700305M7 / APAR700315M7 – 16″ Mid w/ 15″ ATLAS S-ONE MLOK

Also available with the ATLAS R-ONE Handguards


  • M4E1 Threaded Assembled Upper Receiver
  • M-LOK ATLAS S-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.


Product Information

Manufacturer:  Aero Precision
Brand: Aero Precision
SKU: APAR700302M2 | APAR700312M2 | APAR700305M7 | APAR700315M7
Assembled: Yes
Finish: Anodize | Cerakote
Color: Black | FDE
Caliber: 5.56 NATO
Platform: AR15
Complete Upper Series: ATLAS
Handguard Dims: OD:  1.5″ | ID: 1.3″
Handguard Type: M-LOK
Gas Block Diameter: .750
Muzzle Device: A2 Flash Hider
Muzzle Threads: 1/2×28 TPI
Barrel Length: 10.5″ | 16″
Barrel Finish: QPQ Melonite
MSRP: $434.99 to $514.99

[/vc_column_text][porto_block name=”product-arm-or-ally”][vc_separator][vc_column_text]Arm or Ally is a stocking dealer for  Aero Precision, Faxon, Polymer80, Ballistic AdvantageToolcraft, SB Tactical, Holosun and more. See our growing inventory of AR Parts, Firearms and Reloading Components.[/vc_column_text][/vc_column][/vc_row]

Weight N/A
Dimensions N/A
Barrel Length

10.5", 16"

Gas System

Carbine, Mid-Length

Gas Block Diameter


Muzzle Thread

1/2 x 28


5.56 NATO


Black, FDE

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