Daniel Defense MK18 RIII URG 5.56mm 10.3"

Daniel Defense MK18 RIII Upper Receiver Group

The MK18 RIII represents the pinnacle of short-barrel rifle engineering, purpose-built for operators who demand reliability in confined spaces without sacrificing performance.

Key Features

• Barrel Length: 10.3" cold-hammer-forged chrome-lined barrel
• Caliber: 5.56mm NATO
• Configuration: Upper Receiver Group (URG) — pairs with standard AR-15 lower receiver
• Gas System: Optimized for reliability with short-stroke design
• Rail System: Integrated Picatinny rail for optics and accessories
• Finish: Mil-Spec hard-coat anodized black

Performance and Design

Daniel Defense's MK18 RIII builds on decades of combat feedback. The 10.3" barrel delivers effective velocity for defensive distances while maintaining the maneuverability essential for close-quarters work. The upper receiver group format allows you to pair this with your preferred lower receiver, giving you flexibility in your build.

The chrome-lined barrel ensures longevity and corrosion resistance, while the optimized gas system cycles reliably across a wide range of ammunition types. This is a purpose-driven tool for serious shooters.

What You Get

You receive the complete upper receiver assembly — ready to mount on a compatible AR-15 lower receiver. Daniel Defense quality control ensures every component meets exacting standards.

This is professional-grade equipment for those who understand the value of proven design.