400 Legend Upper — CM15 16″ with Selectable Options
The Chattahoochee Munitions CM15 400 Legend Upper combines a 16-inch stainless HBAR barrel, lightweight billet receiver, and 15-inch M-LOK handguard in a color-selectable configuration. Choose your finish and muzzle option, then select whether to include the optional bolt carrier group and charging handle.
This upper belongs to Hall of Legends, our destination for 350 Legend and 400 Legend rifles, magazines, and cartridge education. It provides a component option for customers evaluating the CM15 platform without purchasing a complete rifle.
Understanding the 400 Legend Cartridge
Winchester developed 400 Legend as a straight-wall cartridge for hunting and sport shooting, with intended hunting applications that include deer, hogs, and black bear. Our 400 Legend Guide explains the cartridge’s background, factory ammunition, published ballistics, and role in the CM15.
When choosing ammunition for this upper, consider bullet construction, expected shooting distance, and the barrel length behind published velocity figures. Manufacturer data from a different test barrel should not be treated as measured performance from this 16-inch configuration. Winchester’s cartridge introduction provides additional development background.
For a comparison with a familiar hunting cartridge, read our 400 Legend vs 44 Magnum article, covering rifle ammunition, trajectory considerations, and platform differences.
16-Inch Stainless HBAR Barrel
This 400 Legend Upper uses a 16-inch 416R stainless-steel barrel with an HBAR profile, black Melonite finish, and 1:16 twist. The midlength gas system pairs with a .936-inch gas journal, while 5/8×24 muzzle threads accommodate the selected muzzle device or thread protector.
- Chambering: .400 Legend
- Barrel length: 16 inches
- Material: 416R stainless steel
- Profile: HBAR
- Finish: Black Melonite
- Twist rate: 1:16
- Gas system: Midlength
- Gas journal: .936 inch
- Muzzle threads: 5/8×24
Lightweight Billet Receiver and M-LOK Handguard
The CM15 upper receiver is manufactured from 6061 billet aluminum with reliefs throughout its design. A milled channel in the receiver’s Picatinny rail contributes to the lightweight configuration.
The 15-inch 6061 aluminum handguard provides a full Picatinny top rail and M-LOK attachment capability. QD sockets at 3 and 9 o’clock offer sling-attachment positions. Select the available color option that suits your preferred appearance.
- Receiver: Chattahoochee Munitions lightweight 6061 billet aluminum
- Receiver reliefs and milled Picatinny rail channel
- Handguard: Chattahoochee Munitions 6061 aluminum, 15 inches
- M-LOK attachment capability
- Full Picatinny handguard top rail
- QD sockets at 3 and 9 o’clock
- Selectable color
Adjustable Gas Block and Melonite Gas Tube
A Superlative Arms adjustable gas block and Chattahoochee Munitions Melonite gas tube are included. The adjustable block provides control over gas flow within the operating system. For manufacturer background on its design, see Superlative Arms’ gas-system FAQ.
Optional Bolt Carrier Group and Charging Handle
The bolt carrier group and charging handle are optional selections on this 400 Legend Upper. Review your chosen options before ordering; these components are included only when selected.
Optional CM15 Low Mass Bolt Carrier Group
- Hardened 9310 steel bolt
- 17-4 stainless-steel firing pin
- 8620 steel carrier and key
- Magnetic-particle inspected
- Hardened S7 steel extractor
Optional CM15 Warhammer Charging Handle
The CM15 Warhammer ambidextrous charging handle is offered in collaboration with Breek Arms. Its ambidextrous layout provides charging-handle access from either side of the upper.
Muzzle Device or Thread Protector
Choose a suppressor-host muzzle device or thread protector from the available options. The barrel’s 5/8×24 thread specification describes the mounting interface; a muzzle device or suppressor must also provide appropriate bore clearance for .400 Legend and match the intended mounting system.
Magazines and Cartridge Resources
Use a magazine intended for .400 Legend. Dedicated 400 Legend magazines are available separately from Chattahoochee Munitions, with cartridge-specific geometry for this chambering.
Before hunting, check the current requirements for your location and season, including permitted cartridges, firearm types, and magazine capacity.
Configure Your 400 Legend Upper
Select your preferred color, muzzle option, and optional components to configure this 400 Legend Upper. Explore Hall of Legends for complete CM15 rifles, related accessories, and the guides that connect the cartridge to its hunting applications.
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