Brand: Daniel Defense
Model: MK18 Upper
Platform: AR-15
Caliber: 5.56 NATO
Barrel Length: 10.3"
Gas Block Diameter: .750"
Gas Bock Type: Low-Profile
Barrel Extension: M4
Gas System: Direct Impingement
Muzzle Device: Flash Hider
Muzzle Thread: 1/2 x 28
Receiver Material: 7075-T6 Aluminum
Receiver Finish: Black Anodized
Handguard: Quad Rail
Attachment Style: Picatinny
Bolt Carrier Group: Yes
Charging Handle: Yes
Weight: 4lbs

Features

The MK18 Upper Receiver Group 5.56 NATO from Daniel Defense is a compact, high-performance AR-15 upper designed for reliability, durability, and close-quarters effectiveness. Chambered in 223 Remington and 5.56 NATO, this upper assembly features a 10.3 inch barrel configuration optimized for maneuverability while maintaining consistent ballistic performance. Built to military-grade standards, the MK18 platform is widely recognized for its proven performance in demanding environments.

Constructed with a precision-machined upper receiver and a rugged free-float quad rail handguard, the MK18 provides a stable platform for mounting optics, lights, and other accessories. The design supports reliable cycling and long-term durability, making it well suited for tactical applications, training, and range use. Compatible with standard AR-15 lower receivers, this 5.56 NATO upper receiver group delivers a dependable and compact solution for building or upgrading an AR-15 platform.

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Shipping Restrictions

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.

Daniel Defense MK18 10.3" 5.56 NATO Carbine-Length Upper, Black