Own a true piece of firearm history from the makers of the world's most battle-proven firearms. The FN 15 Military Collector Series M4 upper receiver assembly is a faithful reproduction of the iconic rifle, built to FN's and the U.S. military's exacting standards. Featuring a 14.7 inches button-broached, chrome-lined barrel with a 1:7 twist rate, this upper is engineered for durability and precision. A permanently welded compensator extends the barrel length to 16 inches, ensuring compliance while maintaining the rifle's classic profile. Chambered in 5.56 x 45mm, it is designed to pair seamlessly with the Carpenter 158 steel bolt. Each MIL-SPEC bolt carrier group undergoes rigorous high-pressure and magnetic particle testing, guaranteeing reliability in even the most demanding conditions. Whether completing a build or adding to a collection, this upper receiver assembly delivers the authentic performance and heritage expected from FN.

The Knights Armament M4 RAS adapter rail includes rail adapter covers for enhanced modularity
An M16 style Mil-Spec Bolt Carrier Group features an HPT/MPI tested bolt made from carpenter 158 steel for exceptional durability
The Matech rear sight is engineered for precision, offering quick and accurate targeting with its adjustable features to suit a variety of shooting scenarios
The button-broached, chrome-lined barrel features a 16 inches overall length for superior performance
A2-style compensator (permanently attached), actual barrel length 14.70 inches reduces muzzle rise and recoil for better control

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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.