CM15 300 Blackout 16″ AR15 Rifle – Black Tungsten

300 Blackout Tactical Rifle – CM15 16″ Black Tungsten

The Chattahoochee Munitions CM15 is a complete 300 Blackout tactical rifle manufactured around a tunable operating system, ambidextrous controls and a conventional 16-inch barrel. It is intended for shooters who want the subsonic and suppressor capabilities of 300 Blackout without configuring the firearm as a pistol or federally registered short-barreled rifle.

The CM15 combines a pistol-length gas system, Superlative Arms adjustable gas block, ODIN Works adjustable buffer and CM15 low-mass bolt carrier group. These components allow the firearm to be regulated for its ammunition and suppressor rather than relying on excessive buffer weight to compensate for too much gas entering the action.

Every CM semi-automatic firearm is test-fired and verified for proper operation before shipment. Chattahoochee Munitions addresses gas-block alignment, barrel gas-port sizing and baseline tuning as part of the manufacturing process.

Explore the complete Sector 300 ecosystem for additional CM15 and CM7S firearms, technical resources, magazines and supporting products.

A Full-Length 300 Blackout Tactical Rifle

This 300 Blackout tactical rifle uses a 16-inch CrMV barrel, 15-inch M-LOK handguard and adjustable B5 Systems Bravo stock. The configuration provides the accessory space and familiar handling of a conventional AR-15 rifle while retaining the gas-system characteristics needed for 300 Blackout.

Chattahoochee Munitions considers approximately 10 to 10.5 inches and a 1:5 twist optimal for its preferred subsonic use of the cartridge. Most useful powder consumption occurs within approximately 9 to 10.5 inches. The 16-inch barrel is therefore not presented as producing inherently better subsonic performance or meaningful additional velocity beyond the cartridge’s efficient barrel length.

Instead, this configuration serves customers who want a complete rifle without the federal requirements associated with an SBR. Its 1:7 twist is appropriate to the intended 16-inch configuration, while shorter CM15 models intended for heavier subsonic use employ different twist rates where appropriate.

• Caliber: 300 AAC Blackout / 300 BLK
• Firearm type: Semi-automatic rifle
• Barrel length: 16 inches
• Barrel material: CrMV steel
• Barrel finish: Black nitride
• Twist rate: 1:7
• Crown: Shouldered crown
• Muzzle thread: 5/8×24
• Gas journal: .750 inch
• Gas-system length: Pistol length

Pistol-Length Gas on a 16-Inch Barrel

Barrel length does not determine the correct gas-system length by itself. The pressure characteristics of the cartridge must also be considered. CM uses pistol-length gas on this 16-inch 300 Blackout tactical rifle to preserve reliable operation with subsonic ammunition, particularly when a suppressor is installed.

A longer gas system would place the gas port farther from the chamber, where less pressure is available to operate the action. That can create unnecessary difficulty when cycling lower-pressure subsonic loads. The adjustable gas block controls excess gas when the firearm is used with higher-pressure ammunition or a suppressor that generates substantial backpressure.

Read the complete 300 Blackout gas-system guide for an explanation of gas adjustment, buffer tuning, ejection patterns and suppressor backpressure.

Adjust the Gas Before Adding Buffer Mass

The root cause of an overgassed firearm is the amount of gas operating the action. Adding buffer mass without first adjusting the gas can reduce carrier speed, but it does not prevent unnecessary pressure from being directed into the receiver.

The Superlative Arms adjustable gas block allows gas to be regulated at its source. The ODIN Works adjustable buffer provides a secondary tuning control after the gas setting has been established.

The goal is reliable feeding, extraction, ejection and last-round bolt lock with the lightest practical buffer and the minimum amount of gas required. A correctly tuned 300 Blackout tactical rifle should not be made unnecessarily violent merely to ensure that it cycles.

Subsonic, Supersonic and Suppressor Operation

300 Blackout can operate with subsonic and supersonic ammunition, but those loads do not produce identical pressure. Cycling can even change when switching between different subsonic loads. The adjustable gas block and adjustable buffer allow the operating system to be refined for the ammunition and suppressor actually being used.

An enclosed suppressor is generally preferable when subsonic operation is the primary objective. Its backpressure assists the action when subsonic ammunition produces relatively limited operating pressure. Steel suppressors also typically provide strong sound reduction and a lower perceived tone, although they weigh more than comparable suppressors made from lighter materials.

A flow-through suppressor is generally better suited to supersonic-focused cartridges. Its reduced backpressure can work against reliable cycling with subsonic 300 Blackout ammunition. Conversely, an enclosed suppressor paired with supersonic ammunition can generate considerable backpressure, requiring the gas block to be closed substantially.

For more information about barrel length, twist rate and load selection, read the 300 Blackout subsonic guide. Shooters evaluating purpose-specific loads can also explore ammunition from Black Butterfly Ammunition.

CM15 Billet Receiver Set

The upper and lower receivers are CNC-machined from 7075-T6 billet aluminum. Close receiver fit and an integral trigger guard contribute to the rigid, substantial feel of the CM15 platform. Black Tungsten Cerakote provides the exterior finish for this configuration.

• Mil-spec component interface dimensions
• CNC-machined 7075-T6 billet aluminum construction
• Ambidextrous pictogram-style Safe and Fire markings
• Lightened fire-control-group faces and magazine well
• Integral trigger guard for additional strength
• Machined rather than broached magazine well
• Wide magazine-well flare
• Lower receiver weight of approximately 8 ounces
• Black Tungsten Cerakote finish

Ambidextrous Controls and TriggerTech Duty Options

This 300 Blackout tactical rifle includes ambidextrous primary controls and a customer-selectable TriggerTech AR15 Duty trigger. Available options are single-stage curved, single-stage straight and two-stage straight. All three options have a 3.5-pound total pull weight.

• CM ambidextrous safety selector
• CM ambidextrous magazine release
• CM15 ambidextrous bolt release
• CM15 pivot and takedown pins
• TriggerTech AR15 Duty trigger selected by the customer
• B5 Systems grip in black

Receiver Extension Assembly

• B5 Systems Bravo adjustable stock in black
• CM mil-spec-diameter buffer tube with Black Tungsten Cerakote
• QD receiver endplate
• ODIN Works adjustable AR-15 buffer

CM15 Low-Mass Bolt Carrier Group

The CM15 low-mass bolt carrier group is part of the rifle’s complete operating system. Its mass works in conjunction with the pistol-length gas system, adjustable gas block and adjustable buffer to provide responsive operation without depending on unnecessary gas pressure.

• 9310 steel bolt
• High-pressure-tested bolt
• Magnetic-particle-inspected bolt
• Nitride-coated bolt
• Nitride-coated carrier
• Nitride-coated gas key
• Gas key hardened to USGI specifications
• Grade 8 hardened gas-key fasteners
• Gas key staked to military specifications
• Tool-steel extractor

Upper Receiver Components

• CM15 ambidextrous charging handle machined from 7075 aluminum
• CM15 dust cover
• Forward assist
• Melonite-treated pistol-length gas tube
• Superlative Arms .750-inch adjustable gas block with Melonite finish

15-Inch M-LOK Handguard

The CM15 LWS low-profile handguard gives the 300 Blackout tactical rifle a continuous top rail and attachment space along the sides and bottom. Its 15-inch length provides support for lights, sling hardware, aiming equipment and other appropriately selected accessories.

• 6061 aluminum construction
• Dual-taper attachment system
• Steel barrel nut
• Integrated QD attachment points at the 3 and 9 o’clock positions
• M-LOK attachment surfaces on the sides and bottom
• Continuous Picatinny top rail
• Black Tungsten Cerakote finish
• B5 Systems rail covers in black

Selectable 5/8×24 Muzzle Device

The barrel uses standard 5/8×24 muzzle threads and can be configured with an appropriate muzzle device from the available product options. Customers can select a compatible direct-fire muzzle device or suppressor-mounting interface according to the system they intend to use. Certain selections may change the final price.

Legacy photographs may show a muzzle device that is no longer the default configuration. The completed firearm is not restricted to the device pictured, and the final selection should match the customer’s actual suppressor or unsuppressed requirements.

CM-Vetted ETS Magazine

The rifle includes one CM-vetted ETS 30-round magazine. Chattahoochee Munitions treats magazine selection as part of the firearm’s operating system because cartridge presentation and feeding can vary with different 300 Blackout bullet profiles.

Additional vetted magazines are available through the 300 Blackout magazine product page.

Factory-Tested by Chattahoochee Munitions

Every 300 Blackout tactical rifle manufactured by Chattahoochee Munitions is test-fired and verified for proper semi-automatic operation before shipment. Gas-block alignment, barrel gas-port sizing and baseline tuning are addressed during manufacturing instead of being left as unresolved customer troubleshooting.

The factory setting establishes a reliable operational baseline. Final adjustment may still be appropriate when the customer changes ammunition or adds a suppressor with a significantly different backpressure profile.

Complete Specifications

• Manufacturer: Chattahoochee Munitions
• Model: CM15
• Caliber: 300 AAC Blackout / 300 BLK
• Firearm type: Semi-automatic rifle
• Barrel length: 16 inches
• Barrel material: CrMV steel
• Barrel finish: Black nitride
• Twist rate: 1:7
• Gas system: Pistol length
• Gas block: Superlative Arms .750-inch adjustable
• Buffer: ODIN Works adjustable AR-15 buffer
• Muzzle thread: 5/8×24
• Trigger: TriggerTech AR15 Duty, 3.5-pound total pull
• Handguard: CM15 LWS 15-inch M-LOK
• Magazine: One CM-vetted ETS 30-round magazine
• Finish: Black Tungsten Cerakote with black furniture
• Overall length: 33.25–36.50 inches
• Length of pull: 11.50–14.75 inches
• Weight: 6 pounds, 10 ounces with unloaded magazine and no accessories

Note: Weight and dimensions shown elsewhere in the product interface may represent packaged shipping measurements.

Limited Lifetime Warranty

• Limited to the original purchaser
• Limited regarding functional performance
• Limited regarding the firearm’s original configuration

Frequently Asked Questions

Why does this 16-inch rifle use pistol-length gas?

The pistol-length system provides the gas pressure needed for reliable operation with subsonic ammunition. The adjustable gas block then limits excess gas when higher-pressure ammunition or a high-backpressure suppressor is used.

Can this rifle fire subsonic and supersonic ammunition?

Yes. It can use both, although changing ammunition may require gas adjustment. Even different subsonic loads can produce different cycling behavior.

Is this 300 Blackout tactical rifle suppressor ready?

Yes. The barrel has 5/8×24 muzzle threads and selectable muzzle-device options. An enclosed suppressor is normally preferable when subsonic reliability and maximum sound reduction are the primary objectives.

What is the advantage of the 16-inch barrel?

It provides conventional rifle classification without the federal requirements associated with an SBR. It also permits the use of a 15-inch handguard and a conventional full-length rifle configuration.

Is the firearm tested before shipment?

Yes. Chattahoochee Munitions test-fires every CM semi-automatic firearm and verifies proper operation before shipment.

A Tunable CM15 Rifle Manufactured as a Complete System

The CM15 Black Tungsten 300 Blackout tactical rifle combines a billet receiver set, pistol-length gas system, adjustable gas block, adjustable buffer, TriggerTech Duty trigger and CM-vetted ETS magazine in one complete firearm. Its operating system is manufactured, tested and verified by Chattahoochee Munitions rather than presented as an assortment of unrelated components.