CM15 300 Blackout 7.5″ AR15 SBR or Pistol – FDE Metallic

Compact 300 Blackout Pistol or SBR – CM15 7.5″

The CM15 Compact 300 Blackout is a short, maneuverable AR-15 firearm manufactured by Chattahoochee Munitions for suppressed shooting and applications where overall length matters. Its 7.5-inch barrel, 6.7-inch handguard and adjustable operating system create a highly compact firearm without sacrificing the gas control required for dependable 300 Blackout operation.

This firearm is available as either a pistol or an SBR. Chattahoochee Munitions prefers the stocked SBR configuration when legally practical because the shoulder stock provides greater stability, control and consistency. The pistol remains available for customers whose intended use or ownership requirements favor that classification.

The 7.5-inch barrel prioritizes compact handling over the greater powder utilization available from the 10- to 10.5-inch barrel range. Its 1:5 twist provides the rotational stability needed for long, heavy subsonic bullets fired through a shortened barrel.

Compact 300 Blackout for Confined-Space Handling

This Compact 300 Blackout firearm is designed for customers who knowingly place minimum length ahead of maximum ballistic efficiency. Its short barrel and handguard make it easier to maneuver in confined spaces while helping control the total length added by a suppressor.

The conventional 6.7-inch handguard ends behind the muzzle. This leaves the muzzle device and suppressor attachment interface accessible and distinguishes this model from the CM15 SD, where a portion of the suppressor extends beneath the handguard.

This configuration is particularly well suited to:

• Compact suppressed shooting
• Close-range training and range use
• Confined-space handling
• Property and personal-defense applications
• Vehicle transport where legally permitted
• Customers prioritizing reduced overall length

CM15 Billet Receiver Set

The matched CM15 upper and lower receivers are CNC machined from 7075-T6 billet aluminum. Tight receiver fit, ambidextrous controls and a flared machined magazine well establish a rigid and functional foundation for the complete firearm.

• Mil-spec interface dimensions for AR-15 components
• CNC-machined 7075-T6 billet aluminum construction
• FDE Metallic Cerakote
• 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

Ambidextrous Lower Controls

• CM ambidextrous safety selector
• CM ambidextrous magazine release
• CM15 pivot and takedown pins
• CM15 ambidextrous bolt release
• B5 Systems Coyote grip

TriggerTech Duty Trigger Options

Each Compact 300 Blackout firearm is offered with a TriggerTech AR-15 Duty trigger. Customers can select from three 3.5-pound configurations:

• Single-stage curved
• Single-stage straight
• Two-stage straight with a 3.5-pound total pull weight

TriggerTech’s design provides a clean, predictable break while maintaining the durability appropriate for a working AR-15. Additional information is available directly from TriggerTech.

Pistol or SBR Configuration

Pistol: SBPDW brace and compatible receiver-extension assembly finished in FDE Metallic Cerakote.

SBR: Six-position receiver extension with a B5 Systems Bravo stock.

The SBR is the preferred configuration when its shoulder stock and greater adjustability match the customer’s intended use. An SBR is regulated under the National Firearms Act and must be transferred through an appropriately licensed FFL/SOT following the required federal process. Customers remain responsible for compliance with federal, state and local law.

Both configurations use an ODIN Works adjustable AR-15 buffer. Buffer adjustment complements the adjustable gas block and permits final refinement without relying on unnecessarily heavy reciprocating mass.

CM15 Low-Mass Bolt Carrier Group

• Low-mass carrier configuration
• 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

The upper assembly also includes a CM15 ambidextrous charging handle machined from 7075 aluminum and a CM15 dust cover.

Adjustable Pistol-Length Gas System

The Compact 300 Blackout uses a pistol-length gas system. Pistol gas is necessary for dependable 300 Blackout operation across the cartridge’s wide pressure range, including heavy subsonic ammunition. The 7.5-inch barrel provides sufficient room for pistol gas; CM’s shorter 5-inch configurations require a micro-length system.

• Melonite-treated pistol-length gas tube
• Superlative Arms .750-inch adjustable gas block
• ODIN Works adjustable buffer
• Gas system configured and verified during manufacturing

An adjustable gas block is a requisite component on a properly configured semi-automatic 300 Blackout firearm. Subsonic ammunition, supersonic ammunition and suppressors can create substantially different operating conditions.

The gas block addresses the root cause by controlling how much gas enters the operating system. Buffer adjustment can then provide final refinement when necessary. The objective is reliable operation with the lightest practical buffer and no more gas than the firearm requires.

Every CM semi-automatic firearm is test fired and checked for proper operation before shipment. Gas-port sizing, gas-block alignment and baseline system tuning are addressed during manufacturing rather than being left for the customer to diagnose.

Explore the 300 Blackout gas-system and tuning guide for a detailed explanation of gas adjustment, buffer adjustment, ejection patterns and single-round testing.

Compact 300 Blackout Barrel Specifications

• 7.5-inch barrel length
• 4150 chrome-moly-vanadium steel
• Nitride finish
• 1:5 twist rate
• Shouldered crown
• 5/8×24 muzzle threads
• .750-inch gas-block journal
• Pistol-length gas system

The fast 1:5 twist is especially important in a short barrel. It provides greater rotational stability for long, heavy subsonic bullets than the former 1:7 configuration. This makes the revised barrel substantially better aligned with the suppressed and subsonic purpose of 300 Blackout.

A 7.5-inch barrel does not provide the same powder utilization as CM’s preferred 10- to 10.5-inch configuration. The advantage of this Compact 300 Blackout is its reduced length, especially after a suppressor is added.

SLR Rifleworks ZRO 6.7-Inch Handguard

The firearm uses an SLR Rifleworks ZRO 6.7-inch M-LOK handguard. Its short length provides clearance for the muzzle device and suppressor attachment interface while retaining useful accessory-mounting space.

• 6.7-inch exact length
• 1.35-inch internal diameter
• Free-floating construction
• Mil-spec hardcoat-anodized finish beneath the Cerakote
• Hardcoat-anodized 7075 aluminum barrel nut
• No barrel-nut timing or shims required
• Slip-fit locking attachment system
• Two limited-rotation QD sling sockets
• Continuous Picatinny top rail
• M-LOK accessory-mounting surfaces
• Useful forward mounting space for compatible night-vision and infrared equipment
• FDE Metallic Cerakote

Suppressor and Muzzle-Device Options

The 5/8×24 muzzle threads accept commonly used 300 Blackout muzzle devices and suppressor-mounting systems. Available selections may include direct-thread devices, flash hiders, brakes and suppressor mounts. Pricing may vary according to the device selected.

For subsonic 300 Blackout, an enclosed suppressor is generally preferable to a low-backpressure or flow-through design. Subsonic ammunition often benefits from the additional backpressure supplied by an enclosed suppressor. A flow-oriented suppressor can reduce the operating energy available to cycle the firearm.

Supersonic ammunition used with an enclosed suppressor can generate considerably more backpressure. The adjustable gas block allows the incoming gas to be reduced rather than attempting to mask excessive gas with a heavier buffer alone.

Suppressor choice, ammunition and gas settings function as an interconnected system. Changing any one of them can require adjustment. Even switching between different subsonic loads can affect cycling and ejection behavior.

Subsonic and Supersonic Ammunition

The Compact 300 Blackout can use both subsonic and supersonic ammunition, but its principal purpose is compact suppressed operation with subsonic loads.

Subsonic ammunition provides the cartridge’s defining suppressed capability. Supersonic ammunition produces greater velocity and energy, but it also changes gas-system behavior and creates a ballistic crack that a suppressor cannot eliminate.

Load selection should be based on the intended application, bullet construction and the firearm’s verified operating configuration. Black Butterfly Ammunition is an appropriate source for purpose-designed 300 Blackout ammunition.

Explore the 300 Blackout subsonic guide for additional information about barrel length, twist rate, ammunition and suppression.

CM-Vetted 300 Blackout Magazine

Each firearm includes one CM-vetted ETS 30-round magazine. Magazine performance is evaluated as part of the complete firearm system rather than assuming every nominally compatible AR-15 magazine will feed every 300 Blackout load equally well.

Additional vetted magazines are available through the CM15 300 Blackout magazine page.

Product Specifications

• Manufacturer: Chattahoochee Munitions
• Model: CM15 Compact 300 Blackout
• Caliber: 300 AAC Blackout / 300 BLK
• Classification: Pistol or SBR
• Barrel length: 7.5 inches
• Barrel material: 4150 CMV
• Barrel finish: Nitride
• Twist rate: 1:5
• Gas system: Pistol length
• Gas block: Superlative Arms .750-inch adjustable
• Buffer: ODIN Works adjustable AR-15 buffer
• Muzzle thread: 5/8×24
• Handguard: SLR Rifleworks ZRO 6.7-inch M-LOK
• Trigger: TriggerTech Duty with selectable 3.5-pound configuration
• Magazine: One CM-vetted ETS 30-round magazine
• Finish: FDE Metallic with Coyote furniture
• Overall length: 23.875 to 26.375 inches
• Weight: 6 pounds with an unloaded magazine and no accessories
• Length of pull: 10.25 to 12.75 inches

Note: Weight and dimensions shown on another product tab are for shipping purposes.

Limited Lifetime Warranty

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

Explore Sector 300

This Compact 300 Blackout occupies the conventional-handguard position within CM’s 7.5-inch lineup. Customers seeking greater powder utilization should consider a 10.5-inch CM15. Customers wanting the suppressor recessed beneath the handguard should consider the dedicated 7.5-inch SD configuration.

Explore Sector 300 to compare CM15 semi-automatic firearms, CM7S bolt actions, uppers, barreled actions, magazines and technical 300 Blackout resources.

Frequently Asked Questions

What makes this a Compact 300 Blackout firearm?

The 7.5-inch barrel and 6.7-inch handguard reduce overall length while preserving the adjustable gas and buffer systems needed for dependable operation. The shorter configuration is especially useful when a suppressor will add length beyond the muzzle.

Is this CM15 available as a pistol or an SBR?

Yes. Customers can select a pistol configuration with an SBPDW brace or an SBR configuration with a six-position receiver extension and B5 Systems Bravo stock. CM prefers the SBR when legally practical because the stock provides greater stability and control.

Why does this Compact 300 Blackout use a 1:5 twist?

The 1:5 twist provides increased rotational stability for long, heavy subsonic bullets fired through the short barrel. It is better aligned with the suppressed and subsonic purpose of this firearm than the former 1:7 twist.

Is a 7.5-inch barrel optimal for 300 Blackout?

No. Chattahoochee Munitions considers 10 to 10.5 inches the optimal general-purpose barrel range. The 7.5-inch configuration is intended for customers who deliberately prioritize minimum overall length and maneuverability.

Does this firearm use pistol-length gas?

Yes. The 7.5-inch barrel uses a pistol-length gas system. CM’s shorter 5-inch configurations require a micro-length gas system because they are too short to accommodate pistol gas.

Can a suppressor be installed?

Yes. The barrel has 5/8×24 muzzle threads, and the 6.7-inch handguard leaves the muzzle device and suppressor mounting interface accessible. The suppressor remains forward of the conventional handguard.

Is the suppressor recessed beneath the handguard?

No. This is the conventional 7.5-inch configuration. Customers wanting part of the suppressor beneath the handguard should select the dedicated CM15 7.5-inch SD configuration.

Why are both the gas block and buffer adjustable?

The adjustable gas block controls how much gas enters the operating system and addresses the root cause of overgassing or insufficient operating energy. The adjustable buffer permits final refinement after the gas setting has been established.

Can it use subsonic and supersonic ammunition?

Yes. Different loads and suppressors can change system pressure, cycling and ejection behavior, so gas adjustment may be required when the operating configuration changes.

Is every firearm test fired?

Yes. Every CM semi-automatic firearm is test fired and checked for proper operation. Gas-port sizing, gas-block alignment and baseline tuning are addressed during manufacturing.

What magazine is included?

One CM-vetted ETS 30-round magazine is included. Chattahoochee Munitions evaluates magazine compatibility as part of the complete firearm system.

What are the firearm’s dimensions and weight?

The overall length is 23.875 to 26.375 inches. The firearm weighs 6 pounds with an unloaded magazine and no accessories. Length of pull adjusts from 10.25 to 12.75 inches.