The Aero Precision M4E1 5.56x45mm mid-Length upper receiver is delivered fully assembled, excluding the bolt carrier group and charging handle, which are frequently customized by users. The term "Mid-Length" pertains to the gas tube, which is extended compared to the standard carbine tube, thereby reducing gas velocity and enhancing cycling reliability. At the core of the M4E1 5.56 x45mm mid-Length upper receiver is Aero's forged M4E1 receiver which merges the aesthetic of a machined receiver with compatibility for "mil-spec" components, including the bolt carrier group and charging handle. This receiver is integrated with Aero's latest generation 2 enhanced M-LOK handguard creating a monolithic structure featuring a full-length picatinny top rail and numerous attachment points for M-LOK accessories. Quick detach sling swivel sockets are positioned at the 3, 6 and 9 o'clock positions.

Constructed from 7075-T6 aluminum upper
Precision-machined to M4E1 specifications for the upper receiver
Upper receiver with M4 feedramps
Upper receiver - matte black hardcoat anodized, compliant with MIL-A-8625 type III, class 2 specifications
Laser-engraved T-marks on upper surface
The upper assembly is delivered pre-assembled, including the installation of the port door and forward assist
The upper receiver is compatible with standard AR-15/M16 components
The handguard mounting platform is integrated into the receiver through a forging process
Compatible with Aero Precision handguards and most bar system handguards
The package includes a barrel nut and a wrench
Single-piece free-float design handguard
Handguard - integrated anti-rotation tabs
Handguard - scalloped rail design
Handguard - integrated Continuous top Rail
The handguard features an internal diameter of 1.78 inches, accommodating the majority of muzzle devices and suppressors with a diameter of up to 1-1/2 inches
Handguard designed for compatibility with low-profile gas blocks
Gen 2 handguard - features quick disconnect sling sockets located at the 3, 6 and 9 o'clock positions
Gen 2 handguard enhanced milling on the flat surfaces to improve grip functionality and enhance aesthetic design
Gen 2 handguard enhanced profile for continuous picatinny top rail
5.56x45mm barrel, 16 inches mid-length, 1:7 twist rate, 4150 chrome moly vanadium steel, QPQ finish, gas port drilled
Gas block journal with a diameter of 3/4 inches
Barrel specifications - mid-length gas system, 0.0785 inches gas port diameter
M4 feed ramp extension barrel assembly
Barrel tested by HP and MPI
A2 flash suppressor

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All NFA Rules Apply

These items are controlled by the U.S. Government and authorized for export only to the country of ultimate destination for use by the ultimate consignee or end-user(s) herein identified. They may not be resold, transferred, or otherwise disposed of, to any other country or to any person other than the authorized ultimate consignee or end-user(s), either in their original form or after being incorporated into other items, without first obtaining approval from the U.S. government or as otherwise authorized by U.S. law and regulations.

Local Law Compliance

Certain firearm parts and accessories, including AR-style upper receivers, are subject to complex and frequently changing federal, state, and local laws and regulations. While an upper receiver may be lawfully sold and shipped as a component, the legality of possessing, assembling, configuring, or using an upper receiver in certain states (e.g., California, Washington State) and localities depends on how it is assembled, combined with other components, and ultimately used. You are solely responsible for ensuring that any assembly, configuration, possession, or use complies with all federal, state, and local laws, including any so-called “assault weapon” bans and short-barreled rifle restrictions. We do not provide legal advice and are not responsible for unlawful configurations or uses.