This Aero Precision M4E1 14.5 5.56 Pinned Epsilon 556SL S-ONE includes our 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. 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.
We’ve taken the pain out of building a legal 14.5″ rifle build. These pinned and welded 14.5″ complete uppers feature an Epsilon 556SL that is permanently affixed to the muzzle providing an overall legal length of 16″. Worried you might want to change your gas block? No worries! The outer diameter of the Epsilon 556SL allows you to easily slide your gas block over the muzzle device making it easy to change or service your gas system.
If you’ve had a 14.5″ build planned, but didn’t want to deal with the hassle of getting it pinned and welded or being stuck with a specific configuration, then our 14.5 pinned and welded barrels/uppers are for you!
- M4E1 Threaded Assembled Upper Receiver
- 12″ ATLAS S-ONE M-LOK Handguard
- 14.5″ 5.56 Mid-Length CMV Barrel
- Low Profile Gas Block and Mid Length Gas Tube
- VG6 Epsilon 556SL (pinned and welded)
- Product comes assembled
- This complete upper does not include BCG or Charging Handle.
- The muzzle brake that comes with this complete upper receiver is pinned 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 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