Aero Precision | M4E1-T Complete Upper | 13.9 5.56

This Aero Precision M4E1-T complete upper assembles a forged M4E1 threaded receiver with a 13.9 CMV mid-length barrel and the ATLAS R-ONE slim handguard. The upper ships assembled and is intended for builders or owners fitting a mid-length 5.56 upper onto a compatible lower; the BCG and charging handle are not included. Features emphasize a slim, durable handguard mounting system and an enhanced receiver profile that blends with Aero’Precision Enhanced Series handguards.

Product Specifications

• The manufacturer is Aero Precision.
• The model designation is M4E1-T Complete Upper 13.9 5.56 CMV Mid.
• The UPC is 840014620074.
• The barrel is specified as 13.9 and is chambered for 5.56 NATO.
• The rifling is listed as a 1/7 twist.
• The barrel material/finish is specified as 4150 CrMoV QPQ.
• The gas system is a Mid-Length setup with a low-profile gas block and a mid-length gas tube.
• The gas block journal dimension is listed as .750.
• The handguard is a 12.7 ATLAS R-ONE with a full top picatinny rail.
• The ATLAS R-ONE handguard internal and external diameters are 1.3 inside and 1.5 outside, respectively.
• The handguard includes quick disconnect sling sockets at 3, 6, and 9 o’clock positions.
• The M4E1 threaded upper receiver features an enhanced forging, a new picatinny profile that blends with Enhanced Series handguards, M4 feedramps, laser engraved T-marks, and port door and forward assist installed.
• The product comes assembled as a complete upper and does not include a bolt carrier group (BCG) or charging handle.
• The barrel is noted as HP and MPI tested.
• The package includes a Standard A2 flash hider.

This complete upper blends Aero Precision’s reinforced M4E1 receiver geometry with the lightweight ATLAS R-ONE attachment system to offer a slim, stable mounting platform and a serviceable mid-length gas barrel. Its features make it well suited for precision-oriented range use and for builders seeking a streamlined, lightweight upper that pairs with mil-spec lowers and mid-length gas systems.