This complete upper includes the new ATLAS R-ONE Handguard! The R-ONE handguards are designed with size and weight in mind, while still providing plenty of real-estate to accommodate any attachment needs the end user may have. Our 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.
Includes:
M4E1 Threaded Assembled Upper Receiver
ATLAS R-ONE Handguard of choice
14.5" 5.56 Mid-Length CMV Barrel
Low Profile Gas Block and Mid Length 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. Per the National Firearms Act, the muzzle brake MUST be pinned and welded to achieve the necessary 16" as defined by the ATF for a rifle build.
M4E1 Threaded Upper Receiver Features:
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 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
Learn More about our NEW ATLAS Handguards
14.5" 5.56 Mid-Length Barrel Features:
Chamber: 5.56
Length: 14.5"
Twist: 1 in 7
Threading: 1/2"x28
Material: Chrome Moly Vanadium
Finish: QPQ corrosion resistant finish both inside and out
Gas Block: .750
Gas Port: .0785
Gas System Length: Mid
Weight: 26oz
M4 Barrel Extension
HP and MPI Tested