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 5.56mm 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. The extended handguard conceals the low-profile gas block, while the milled texturing on the flats provides an improved gripping surface and contributes to the firearm's distinctive appearance.

Receiver constructed from forged 7075-T6 aluminum, featuring a MIL-A-8625 type III class 2 hardcoat anodized finish
Ejection port cover and forward assist have been installed
Barrel constructed from 4150 chrome-molybdenum-vanadium steel, featuring a 1:7 twist rifling and finished with a black QPQ coating
Intermediate length gas system
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
The A2-style flash suppressor is installed but is neither pinned nor welded
1/2-28 TPI muzzle threads
1/4 inches diameter pivot and takedown pin holes

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It is the customer’s responsibility for understanding state laws regarding all purchases made. For a comprehensive list of all Shipping Restrictions, please refer to our Shipping Restrictions By State Page found Here.

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.