UppersPremium

CMMG

CMMG Mk4 9mm RDB Complete Upper

Radial Delayed Blowback 9mm upper setup for standard AR-15/Mk4 lowers using CMMG ARC conversion magazines.

No image available

Affiliate links (?)

Check Best Price

View at Brownells

Add to Build

Quick Specs

Price: $850
Weight: N/A
Brand: CMMG
Category: upper

Features

•9mm Radial Delayed Blowback
•Mk4 / standard AR-15 lower setup
•Pairs with CMMG 9 ARC magazines
•Complete upper-group shortcut
•Picatinny top rail and M-LOK handguard

Capability Boosts

Reliability+1

Mobility+1

Recommended For

Home Defense

Duty/Patrol

Vehicle Operations

Outdoor Defense

Compatibility Tags

family: pccfamily: ar-patternplatform: custom-ar-9caliber: 9mmmag-type: cmmg-arcthread: 1/2x28interface: picatinny-tophandguard: mlokbarrel: compactar9-system: cmmg-rdb

Compatible Platforms

Custom

Custom AR-9 (Build From Scratch)

Pairs Well With

Top matches

Burn Proof Gear

Burn Proof Gear BP-15 Gen 1 11.3"

5 shared compatibility tags

Excellent

Heckler & Koch

HK MR556 A4 SBR 11"

5 shared compatibility tags

Excellent

Knights Armament Company

Knights Armament SR-15 CQB 11.5"

4 shared compatibility tags

Great

Geissele

Geissele Super Duty 11.5"

4 shared compatibility tags

Great

Geissele

Geissele Super Duty 12.5"

4 shared compatibility tags

Great

Custom

Custom AR-9 (Build From Scratch)

7 shared compatibility tags

Great

Similar Products

CMMG

CMMG Mk9 9mm RDB Complete Upper

$850

Colt

Colt LE6920 EPR Complete Upper (16" M-LOK)

$1,149

Geissele Automatics

Geissele Super Duty Complete Upper

$1,199

Geissele Automatics

Geissele Super Duty 11.5" Complete Upper

$1,199

Related Guides & Articles

Guides

Best AR-15 for Hunting 2026: Top 5 Hunting Rifles Ranked (Wilson Combat, Springfield, Ruger, CMMG)

gear•12 min read

How to Build an AR-15: Complete Parts List & Step-by-Step Guide (2026)

setup•8 min read

AR-15 Night Vision Setup 2026: Complete Guide (PEQ-15, DBAL, Optic Heights)

thermal•8 min read

Articles

SIG Sauer P226: Complete History from XM9 Trials to Legion X5

industry•Feb 26, 2026

LMT Hybrid MRP Uppers: M-LOK Meets Monolithic at SHOT Show 2026

news•Jan 22, 2026

Browse all guides →Browse all articles →

Build Your Custom Configuration

Add the CMMG Mk4 9mm RDB Complete Upper to your build and see how it enhances your platform.

Start Building