Chattahoochee Munitions tests and supplies the CM7S 300 Blackout Bolt Action Magazine, the 10-round Magpul PMAG 10 5.56 AC in the short-action AICS pattern, and ships one with every complete CM7S 300 Blackout firearm.
CM7S 300 Blackout Bolt Action Magazine – 10-Round AICS
This 300 Blackout bolt action magazine is the 10-round Magpul PMAG 10 5.56 AC that Chattahoochee Munitions has tested and vetted for use in CM7S firearms chambered in 300 BLK. Its AICS-pattern design works with the CM7 chassis and provides the cartridge presentation needed for the CM7S bolt face to engage and feed 300 Blackout ammunition.
Magazine selection is particularly important when using a .223-based cartridge in an AICS-pattern bolt-action platform. The PMAG’s offset feed-lip geometry and single-stack, constant-curve internal design help position cartridges for proper bolt engagement. CM recommends this magazine based on testing conducted in the CM7S rather than simply assuming that every .223-pattern AICS magazine will feed 300 BLK reliably.
Explore the complete family of CM7S 300 Blackout firearms and barreled actions, or visit Sector 300 to compare the complete CM 300 Blackout ecosystem.
CM-Vetted for the CM7S
Chattahoochee Munitions vets the magazines offered for our firearms and their stated caliber applications. This 300 Blackout bolt action magazine has been tested with the CM7S platform and is the magazine CM recommends for its 300 BLK bolt-action firearms.
The underlying PMAG 10 5.56 AC is manufactured by Magpul as a 5.56×45 NATO and .223 Remington magazine for short-action AICS-pattern bottom metal. Magpul does not provide a general recommendation for using this magazine with 300 Blackout. CM’s recommendation is specific to our testing of the magazine with the CM7S 300 BLK system.
This product should not be interpreted as a universal magazine recommendation for every AICS-pattern 300 Blackout firearm. Differences in actions, bolt faces, bottom metal, magazine positioning and ammunition can affect feeding. CM’s validation applies to the stated CM7S application.
Offset Feed-Lip Geometry
The PMAG 10 5.56 AC incorporates offset feed-lip geometry designed to improve bolt-face engagement with .223-based cartridges. This addresses a common challenge encountered when small-diameter cartridges are used in AICS-pattern systems originally associated with larger short-action cartridges.
Proper bolt engagement helps the bolt face capture the cartridge as it moves forward from the magazine. The single-stack, constant-curve internal geometry maintains controlled cartridge presentation throughout the magazine’s 10-round capacity.
These design characteristics are important to the performance of a 300 Blackout bolt action magazine. They help support consistent feeding while preserving the detachable AICS-pattern magazine architecture used by the CM7 chassis.
Magazine Features
- CM application: Tested and vetted for CM7S firearms chambered in 300 BLK
- Capacity: 10 rounds in the CM7S 300 Blackout application
- Magazine pattern: Short-action AICS
- Manufacturer: Magpul Industries
- Manufacturer model: PMAG 10 5.56 AC
- Manufacturer SKU: MAG1100
- Construction: Impact- and crush-resistant GEN M3 polymer
- Feed geometry: Offset feed lips designed to improve bolt-face engagement
- Internal geometry: Single-stack, constant-curve design
- Follower: Self-lubricating follower for smooth movement
- Spring: Long-life stainless-steel spring
- Handling: Low-profile ribs with aggressive front and rear texture
- Floorplate: Flared for positive handling and removal
- Identification: Paint-pen dot matrix for caliber or load marking
- Maintenance: Quickly disassembles for inspection and cleaning
- Country of manufacture: Made and engineered in the USA
Positive Handling and Identification
Low-profile ribs and aggressive front and rear texturing give the shooter positive control when inserting or removing the magazine. The flared floorplate provides an additional gripping surface, which can be useful when removing the magazine from a chassis or retrieving it from a pouch.
A paint-pen dot matrix on the base allows the magazine to be clearly marked for 300 BLK. Dedicated identification is strongly recommended when the shooter also owns firearms chambered in .223 Remington or 5.56 NATO.
Clear caliber markings reduce the possibility of ammunition or magazine confusion. Always confirm the firearm’s chambering and the ammunition headstamp before loading.
Subsonic 300 Blackout Ammunition
The 1:5 twist Mos-Tek barrel on the 300 Blackout Bolt Action Magazine is designed for subsonic 300 Blackout, where long, heavy bullets need that spin to stay stable at about 1,000 fps. Chattahoochee Munitions designs its 1:5 barrels for subsonic loads, not supersonic; for supersonic 300 Blackout, choose the 16-inch CM15 with its 1:7 twist.
The CM7S has no gas system, so changing between subsonic loads needs no gas or buffer adjustment. Point of impact and terminal performance still change between loads, so confirm each load before relying on it. For hunting, choose a bullet designed to expand at subsonic impact speed.
Black Butterfly Ammunition offers 300 Blackout subsonic loads, including expanding designs. Read the 300 Blackout subsonic guide and 300 Blackout twist rate.
Inspection and Maintenance
The removable floorplate permits quick disassembly for routine cleaning. Periodically inspect the feed lips, follower, spring and magazine body for contamination or damage. Keep the interior free of excessive oil, dirt and debris that could interfere with follower movement.
Do not alter the feed lips or internal geometry. If the magazine develops visible damage or repeatable feeding problems, remove it from service and contact Chattahoochee Munitions for assistance.
Complete the CM7S System
This 300 Blackout bolt action magazine supports the complete CM7S family, including compact chassis firearms and CM7S barreled actions installed in compatible AICS-pattern systems. It provides a tested magazine solution for customers purchasing a complete CM7S firearm or completing a rifle around a CM7S barreled action.
For the manufacturer’s original 5.56/.223 specifications, dimensions and product information, visit the Magpul PMAG 10 5.56 AC product page.
Compatible Chattahoochee Munitions Firearms
CM vets this magazine for the CM7S 300 Blackout family:
- 8-inch CM7S: 300 Blackout truck gun, 300 BLK bolt action pistol and suppressor ready 300 Blackout pistol
- 10-inch CM7S: suppressed 300 Blackout hunting rifle, 300 Blackout deer hunting rifle and 300 Blackout bolt action SBR
- 12.5-inch CM7S: 300 Blackout hunting rifle with WOOX walnut furniture
- CM7S barreled actions in a compatible AICS-pattern chassis: 8, 10 and 12.5 inches
Cartridge dimensions follow the ANSI/SAAMI centerfire rifle standard. Every CM7S 300 Blackout barrel is a 1:5 twist designed for subsonic loads.
300 Blackout Guides
- What Is 300 Blackout?: why 300 Blackout and 5.56 must be kept apart
- 300 Blackout bolt action vs semi-auto: 30-round AR15 or 10-round AICS
- 300 Blackout subsonic: heavy subsonic loads and feeding
300 Blackout Bolt Action Magazine FAQ
What magazine does the CM7S 300 Blackout use?
The 10-round Magpul PMAG 10 5.56 AC in the short-action AICS pattern, tested by Chattahoochee Munitions with the CM7S and CM7 chassis.
Will any AICS magazine feed 300 Blackout in the CM7S?
Not necessarily. CM recommends this PMAG because its offset feed lips present the small .223-based case to the bolt face.
Does a complete CM7S 300 Blackout include this magazine?
Yes. Every complete CM7S 300 Blackout firearm ships with one.
Will it fit a third-party chassis?
It follows the short-action AICS pattern, but fit and feeding in other chassis and bottom metal are not guaranteed by Chattahoochee Munitions.
Who makes the CM7S 300 Blackout magazine?
Magpul manufactures the PMAG 10 5.56 AC. Chattahoochee Munitions tests it with the CM7S 300 Blackout and includes one with every complete CM7S 300 Blackout firearm.
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