The Daniel Defense MK18 RIII Upper Receiver Group (brand part number 23-004-81721-011) is a 10.3-inch upper built to the specs of Daniel Defense’s well-known MK18-pattern short-barreled AR-15 platform, finished in Flat Dark Earth. It ships with no sights, giving the buyer a clean slate to run their own optic and backup irons. This is an upper receiver group only, with no lower receiver included, so it is not itself a regulated firearm.

Key Specifications

• Chambered in .223 Rem/5.56 NATO, the standard AR-15 caliber with wide ammunition availability.
• Barrel length measures 10.3 inches, matching Daniel Defense’s well-known MK18 short-barrel configuration.
• Rate of twist is 1-in-7, matched to a wide range of .223/5.56 bullet weights.
• Sights are not included, leaving the top rail clear for the buyer’s own optic and backup irons.
• Configuration is Daniel Defense’s Accessory-Uppers product line, built as a complete drop-in upper group.
• Finish is Flat Dark Earth, a popular tan color option for a desert or field-ready look.

Frequently Asked Questions

Is this bare upper itself an NFA-regulated item? No. It is an upper receiver group with no lower receiver included, so it is not a regulated firearm on its own. Installing it on a shouldered, rifle-configured lower without a registered short-barreled rifle would require ATF Form 1 approval first.

Is this a complete rifle? No, this is an upper receiver group only with no lower receiver included. It ships without an FFL transfer and needs a compatible AR-15 lower to complete a rifle.

What does URG mean? URG stands for Upper Receiver Group, meaning the barrel, bolt carrier group, and handguard ship assembled as one unit ready to mate to a compatible lower.

Buy the Daniel Defense MK18 RIII URG, 10.3in, FDE

Order this Daniel Defense MK18 RIII upper receiver group in Flat Dark Earth from a Lubbock, Texas gun shop for your next compact AR build. Browse more complete uppers in our AR15 uppers selection.