CMMG RESOLUTE MK4 COMPLETE UPPER - 350 LEG - 16.1" - BLACK
CMMGThe CMMG Resolute MK4 Complete Upper in 350 Legend delivers a powerful, versatile AR-platform upper receiver built for hunters, sport shooters, and home defenders who demand reliable performance in a straight-walled cartridge. With a 16.1" barrel and classic black finish, this complete upper is a purpose-built upgrade or starting point for any MK4-compatible lower.
- Chambered in 350 Legend — ideal for deer hunting and range use
- 16.1" barrel delivers optimal velocity and legal hunting compliance
- CMMG's precision-machined MK4 upper receiver for consistent performance
- Matte black finish resists corrosion and withstands hard field use
- Ships as a complete upper — bolt carrier group and charging handle included
- Compatible with any standard AR-15 MK4 lower receiver for easy pairing
Who This Is For
This upper is an excellent choice for deer hunters in states requiring straight-walled cartridges, AR enthusiasts looking to expand their caliber options, or anyone building a hard-hitting yet low-recoil rifle on a standard AR-15 platform. It suits both first-time builders and experienced shooters seeking a quality factory-assembled upper without the guesswork.
Specifications
| Brand | CMMG |
|---|---|
| Model | Resolute MK4 Complete Upper |
| Caliber | 350 Legend |
| Barrel Length | 16.1" |
| Finish | Black |
| Platform | AR-15 / MK4 |
| Action Type | Semi-Automatic (Upper Only) |
| Upper Receiver | Forged 7075-T6 Aluminum |
| Handguard | M-LOK Compatible Rail |
| Includes | BCG, Charging Handle |
| Lower Compatibility | Standard AR-15 MK4 Lower |
| Country of Origin | USA |
Frequently Asked Questions
Will this upper work with my existing AR-15 lower receiver?
Yes — the CMMG Resolute MK4 Complete Upper is designed to pair with any standard AR-15 MK4 lower receiver using standard takedown and pivot pins. However, because 350 Legend uses a unique bolt face, you will need 350 Legend-specific magazines. CMMG recommends using magazines designed for this cartridge to ensure reliable feeding.
Is 350 Legend a good cartridge for deer hunting?
Absolutely. The 350 Legend was specifically engineered as a straight-walled hunting cartridge, making it legal for deer hunting in many Midwestern and Eastern states that prohibit bottleneck rifle cartridges. It produces moderate recoil, excellent terminal performance on deer-sized game, and is highly effective at ranges out to 200 yards — making this upper a smart choice for hunters seeking a capable, comfortable hunting rifle.
Does this come with everything I need to complete the rifle?
The CMMG Resolute MK4 Complete Upper includes the upper receiver, 16.1" barrel, handguard, bolt carrier group (BCG), and charging handle — everything above the lower. To build a complete, functional rifle, you will need to add a compatible AR-15 MK4 lower receiver (stripped or complete), a 350 Legend magazine, and your preferred stock or pistol brace assembly. No gunsmithing is required to mate this upper to a standard lower.