Brownells 75th Anniversary - A Shooting Heritage
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This complete upper includes Aero Precision’s new ATLAS S-ONE Handguard! The S-ONE line of 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.

  • M4E1 Threaded Assembled Upper Receiver
  • Choice of 12” or 15” M-LOK ATLAS S-ONE Handguard
  • 16" 5.56 Mid CMV Barrel, 18” Rifle Barrel
  • Low Profile Gas Block and Mid-Length/Rifle Length Gas Tube Depending on Configuration
  • Product comes assembled
  • This complete upper does not include BCG or Charging Handle
  • 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 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

16" 5.56 Mid Barrel Features:

  • 5.56 NATO 16" Barrel, 1/7 twist, 4150 CrMoV, QPQ, gas port drilled
  • Mid-length gas system, .0785 gas port
  • M4 Feed Ramp Extension
  • HP and MPI tested
  • Standard A2 flash hider

18" 5.56 Rifle Length Barrel Features:

  • 5.56 Nato 18" Rifle Length Barrel
  • 4150 CrMoV w/ QPQ finish
  • 1/7 twist
  • .750 gas block journal
  • Rifle length gas system
  • M4 Feed Ramp Extension
  • HP and MPI tested
  • Standard A2 flash hider

AERO PRECISION - M4E1 UPPER RECEIVERS COMPLETE 5.56MM

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In Stock

Cartridge: 5.56 mm NATO

Finish: Black

Style: Complete

Length: 16"

Twist: 1-7

Online Only
In Stock

Cartridge: 5.56 mm NATO

Finish: Black

Style: Complete

Length: 16"

Twist: 1-7

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Out of Stock

Cartridge: 5.56 mm NATO

Finish: Black

Style: Complete

Length: 18"

Twist: 1-7