CMMG Resolute MK4 Upper Group – 5.56×45, 16.1″ Barrel

Description

This CMMG Resolute Mk4 upper group is a partial AR-15 upper assembly chambered for .223 Rem/5.56 NATO. It is built around a 16.1-inch steel barrel with a free-float M-LOK handguard and ships without a bolt carrier group or charging handle. The package includes an A2-style flash hider on 1/2-28 threads and a non-adjustable .750 gas block, making it suitable for finishing a custom build or replacing an existing upper assembly.

Key Specifications

• The upper is chambered in .223 Rem/5.56 NATO.
• The barrel measures 16.1 inches.
• The barrel twist rate is 1:7″.
• The barrel material is steel.
• The barrel finish is listed as Matte Black in source material.
• The handguard is a M-LOK free-float CMMG EML 15 style handguard with Armor Black finish listed for the handguard.
• The muzzle is threaded 1/2-28 and includes an A2 flash hider.
• The gas system uses a non-adjustable .750 gas block.
• The package is a partial upper group and ships with no bolt carrier group or charging handle.

The Resolute MK4 upper group gives builders a practical, component-level foundation for a reliable AR-platform rifle. With a mid-length barrel profile, proven 1:7″ twist, and a free-float M-LOK handguard, this assembly is well suited for general-purpose shooting and finishing a custom rifle build where consistent components and straightforward configuration matter.

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