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Customer Reviews
Helpful Positive Review
Best Upper I Have Purchased by Noah, Verified Owner, October 30, 2024
This upper will not disappoint. The accuracy of this barrel is spot on and had zero problems.
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Helpful Positive Review
“Fast shipping, unbeatable prices—Optics Planet delivers again! Adding the Daniel Defense MK18 RIII to my collection was a no-brainer. Outstanding service and a flawless product. Highly recommend!”
1/1 found this helpful
Most Recent Reviews
DD MK18 Is All the Hype by Michael, Verified Owner, March 15, 2026
The MK18 RIS III upper from DD is beefy. Unlike many other hand guards, there is virtually no deflection. Fit and finish are what you would expect from DD, very smooth with no machining “grabs” like in lower quality builds. Wasn’t sure how I was goin...
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Most Recent Reviews
Upper Receiver by hay, March 4, 2026
Very good upper receiver. Strong and accurate. Very solid materials highly recommend
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Product Info for Daniel Defense MK18 RIII URG 10.3 inch 5.56x45mm NATO Upper Receiver with Flash Hider Assembly

The MK18 RIII AR15 style Upper Receiver Group is unmatched in size, weight, and performance, and is built around a 10.3 inch Cold Hammer Forged M4 Profile barrel with a Daniel Defense Flash Suppressor, a GRIP-N-RIP Charging Handle, and our carbine length gas system. It features a 9.5 inch lightweight RIS III railmodeled after the revolutionary RIS II two-piece handguard developed for SOCOM which features M-LOK attachment for lighter weight. All Daniel Defense complete upper receiver groups come standard with an M16 profile bolt carrier group.image

NFA DISCLAIMER

Once this part is assembled into a complete firearm, it becomes a regulated item by the National Firearms Act (NFA). Please check with your local and state municipalities for any further regulatory requirements. It is the buyer's responsibility to make sure they comply with all NFA rules and applicable laws.

Specifications for Daniel Defense MK18 RIII URG 10.3 inch 5.56x45mm NATO Upper Receiver with Flash Hider Assembly:

Manufacturer: Daniel Defense
Caliber: 5.56x45mm NATO
Overall Length: 19.3 in
Barrel Length: 10.3 in
Barrel Profile: Government
Gas System Length: Carbine Length
Barrel Twist Rate: 1-7
Muzzle Device: Flash Suppressor
Finish: Salt Bath Nitride
Gun Model: AR-15
Fabric/Material: Multiple
Handguard Length: 9.5 in
Gun Rail: M-LOK
Gun Type: Rifle
Gun Make: Daniel Defense
Barrel Material: Chrome Moly
Bolt Carrier Group Included: MIL-SPEC
Charging Handle Included: MIL-SPEC
Magazine Included: No
Condition: New
Threads per Inch: 1/2x28
Mount Type: M-LOK
Gas System: Carbine Length

Features of Daniel Defense MK18 RIII URG 10.3 inch 5.56x45mm NATO Upper Receiver with Flash Hider Assembly:

  • UPPER RECEIVER: Mil-Spec with Indexing Marks and M4 Feed Ramps. CNC Machined of 7075-T6 Aluminum, Type III Hard Coat Anodized
  • BARREL: Chrome Moly Vanadium Steel, Cold Hammer Forged, 1:7 Twist, 10.3 inch Government Profile, Chrome Lined, Mil-Spec Heavy Phosphate Coated, and HP/MPI Tested
  • GAS SYSTEM: Pinned Low Profile Gas Block CNC Machined of 4140 hardened steel with Mil-Spec Heavy Phosphate Coating, Carbine Length, Direct Impingement
  • MUZZLE DEVICE: Daniel Defense Flash Suppressor, 17-4 PH Stainless Steel, Salt Bath Nitride Finished
  • BOLT CARRIER GROUP: M16 Profile, Mil-Spec MP Tested, Chrome Lined, Properly Staked Gas Key
  • SIGHTS: Sold Separately
  • HANDGUARD: Daniel Defense RIS III 9.5, Patented, 6-Bolt Bolt-Up System, CNC Machined of 6061-T6 Aluminum
  • CHARGING HANDLE: GRIP-N-RIP Charging Handle, Body CNC Machined of 7076-T6 Aluminum, Handles & Latch CNC Machined of 6061-T6 Aluminum, Heavy Duty Stainless Steel Roll Pins, Type III Hard Coat Anodized

Package Contents:

  • Daniel Defense MK18 RIII URG 10.3 inch 5.56x45mm NATO Upper Receiver with Flash Hider Assembly

Daniel Defense MK18 RIII URG 10.3 inch 5.56x45mm NATO Upper Receiver with Flash Hider Assembly Orderable Models

List of Orderable Models

  • Daniel Defense Upper Receiver with Flash Hider Assembly MK18 RIII URG, 5.56x45mm NATO, 19.3 inch, 10.3 inch Barrel, Government Profile, Carbine Length, 1-7 Twist, 1/2x28 Thread, M-LOK Handguard, Flash Suppressor, Salt Bath Nitride, BLK, 23-004-81721-006 , MPN: 23-004-81721-006 , UPC: 818773023351 , Code: DDD-UFH-M18R3U10-23-004-81721-006
  • Daniel Defense Upper Rec w/ FH Assy MK18 RIII URG, 5.56 NATO, 19.3in, 10.3in BBL, Govt Prof, Carbine, 1:7, 1/2x28, M-LOK Hndgrd, Flash Supp, Nitride, FDE, 23-004-81721-011 , MPN: 23-004-81721-011 , UPC: 818773023016 , Code: DDD-UFH-M18R3U10-23-004-81721-011

Daniel Defense MK18 RIII URG 10.3 inch 5.56x45mm NATO Upper Receiver with Flash Hider Assembly Unavailable & Discontinued Models

List of Unorderable Models

  • DEMO, Daniel Defense Upper Rec w/ FH Assy MK18 RIII URG, 5.56 NATO, 19.3in, 10.3in BBL, Govt Prof, Carbine, 1:7, 1/2x28, M-LOK Hndgrd, Flash Supp, Nitride, FDE, 23-004-81721-011 , MPN: 23-004-81721-011-DEMO , Code: DDD-UFH-M18R3U10-23-004-81721-011-DEMO
  • USED Daniel Defense Upper Receiver with Flash Hider Assembly MK18 RIII URGBLK, 23-004-81721-006, EDEMO1 , MPN: 23-004-81721-006-EDEMO1 , Code: DDD-UFH-M18R3U10-23-004-81721-006-EDEMO1
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Last updated 2026-06-26 UTC.