Aero Precision 300 Blackout M4E1 ATLAS S-ONE Complete Upper


Fully Assembled and Warrantied by Aero Precision.  Ships for FREE


Aero Precision 300 Blackout M4E1 ATLAS S-ONE Complete Upper

Available in black or FDE with your choice of 3 barrel lengths.

Aero Precision 300 Blackout 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.
**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

300 BLK Barrel Features:

  • Select between a 8″, 10″ or 16″ barrel.
  • .300 Blackout 1/7 twist, 4150 CrMoV, QPQ, gas port drilled
  • .750 gas block journal
  • Gas Port: .0935
  • Pistol length gas system.
  • M4 Feed Ramp Extension
  • M4 Barrel Extension
  • HP and MPI tested
  • Standard A2 flash hider

Choose between 3 Configurations:

APAR700301M1 / APAR700311M1 – 8″ Barrel w/ 7″ ATLAS S-ONE MLOK
APAR700302M4 / APAR700312M4 – 10″ Barrel w/ 9″ ATLAS S-ONE MLOK
APAR700305M14 / APAR700315M14 – 16″ Barrel 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
  • 8″, 10″, or 16″ 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: APAR700301M1 | APAR700311M1 | APAR700302M4 | APAR700312M4 | APAR700305M14 | APAR700315M14
Assembled: Yes
Finish: Anodize | Cerakote
Color: Black | FDE
Caliber: .300 Blackout
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: 5/8×24 TPI
Barrel Length: 8″ | 10″ | 16″
Barrel Finish: QPQ Melonite
MSRP: $439.99 to $524.99

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Weight N/A
Dimensions N/A

Black, FDE

Barrel Length

10", 16", 8"

Gas System


Gas Block Diameter


Muzzle Thread

5/8 x 24


300 Blackout

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