M4E1 15" ATLAS R-ONE M-LOK Complete Upper, 16" 5.56 HBAR CMV Mid-Length Barrel - Anodized Black

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This complete upper receiver incudes an HBAR profile barrel that is laser marked "HBAR".


  • M4E1 Enhanced Assembled Upper Receiver
  • 15" ATLAS R-ONE M-LOK Handguard
  • 16" 5.56 HBAR barrel
  • 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.

M4E1 Upper Features:

  • Forged from 7075 T6 aluminum
  • Precision machined to M4E1 specs
  • M4 feedramps
  • Matte black hard coat anodized Mil 8625 Type 3 Class 2
  • Laser engraved T-marks
  • Comes assembled, with port door and forward assist installed
  • Accepts standard AR15/M16 components
  • Handguard mounting platform is forged into the receiver
  • Works with Aero Precision handguards but also fits most BAR-system handguards
  • Barrel nut and wrench are included

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
  • 1.3" Inside diameter
  • 1.5" Outside diameter
  • Compatible with mil-spec AR15 upper receivers and barrels
  • MLOK attachment points

16" 5.56 HBAR Barrel

  • 5.56 Nato 16" Barrel, 1/7 twist, 4150 CrMoV, QPQ, gas port drilled
  • .750 gas block journal
  • Mid-Length Gas System
  • M4 Feed Ramp Extension
  • HP and MPI tested
  • Standard A2 flash hider
Shipping to FFL Dealer RequiredNo
Made In America?Yes
Caliber5.56 NATO
Barrel Length16"
Select Your FinishAnodized Black
Finish Your Build
  1. 5.56 Bolt Carrier Group, Complete - Black Nitride
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    Special Price $104.99 Regular Price $149.99

  2. Aero Precision 5.56 Bolt Carrier Group - Bolt View
    5.56 Bolt Carrier Group, Complete - Phosphate
    Special Price $101.49 Regular Price $144.99

  3. Aero Precision AR15 Ambidextrous Charging Handle
    AR15/M4 5.56 Ambidextrous Charging Handle
    Special Price $66.98 Regular Price $79.99

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