Cmmg Resolute Mk4 5.56Nato Assembl Upper 14.5''Bbl W/P&W Brake Blk

The CMMG Resolute Mk4 5.56 NATO assembled upper receiver is engineered for shooters who want a short, legal rifle without the paperwork. This 14.5-inch barrel upper comes factory-assembled with a pinned and welded CMMG ZEROED SVD muzzle brake—no extra gunsmithing needed. The fixed brake extends overall length to meet federal rifle requirements while keeping your bore as short as possible, so you get a nimble package that operates under standard Title I rules. If you're building a compact patrol rifle, home-defense AR, or a lightweight field gun and want to skip the NFA registration process, this upper delivers the goods out of the box.

The upper itself is built from billet 6061-T6 aluminum and wears a durable Cerakote finish. Its M-LOK handguard gives you clean mounting options for lights, optics, and accessories without clutter. The barrel is 4140CM steel with a 1:7 twist—standard fare for reliable 5.56 performance across the full spectrum of factory and loaded ammunition. Mid-length gas system with a fixed block keeps the operating cycle predictable and low-stress. At just 4.1 pounds and 23.8 inches long, this is a handy upper that won't wear you down over a long day at the range or in the field.

Note that this is an upper receiver only—you'll need to source your own bolt carrier group and charging handle to complete the build. If you already have a lower and those components on hand, you're minutes away from a running gun. The RESOLUTE name reflects CMMG's philosophy: get the essentials right, skip the hype, and let the rifle speak for itself.

Key Features

• 14.5-inch barrel with pinned and welded muzzle brake—no SBR tax stamp required
• CMMG ZEROED SVD brake optimizes recoil management and flash suppression
• Billet aluminum upper receiver for durability and precision
• M-LOK integrated handguard for modern accessory mounting
• 1:7 barrel twist handles the full range of 5.56 NATO loads
• Mid-length gas system strikes a balance between reliability and controllability
• Cerakote finish resists corrosion in field conditions

Specifications

Frequently Asked Questions

Do I need a tax stamp or SBR registration for this upper?

No. The pinned and welded muzzle brake is legally fixed to the barrel, adding length so the complete rifle meets the federal minimum 16-inch barrel requirement. As long as you pair it with a standard lower and keep overall length above 26 inches, you're operating as a legal Title I rifle without NFA paperwork.

What do I need to complete a rifle with this upper?

This upper receiver does not include a bolt carrier group or charging handle. You'll need to supply those components separately, along with a lower receiver and magazine, to build a complete rifle.

What ammunition does the 1:7 barrel twist handle best?

A 1:7 twist is the standard for modern 5.56 NATO and works reliably across the full range of factory and reloaded loads—from lightweight varmint rounds to heavy 77-grain match ammunition.

Is the muzzle brake removable?

No. The CMMG ZEROED SVD brake is pinned and welded to the barrel, which is how it achieves the overall length needed to avoid NFA registration. It cannot be swapped out without significant gunsmithing.