8.6 BLK SBR | CM7S Bolt Action 8″ Black Tungsten
The CM7S 8.6 BLK SBR combines an 8-inch barrel with the Chattahoochee Munitions CM7S bolt action, billet CM7 chassis, TriggerTech Primary trigger, telescoping stock and vetted AICS-pattern magazine system. At just 5 lb 12 oz with an adjustable overall length of 20.50 to 28.0 inches, this configuration is built around minimum overall size.
Finished in Black Tungsten Cerakote with black furniture, the 8-inch CM7S is particularly well suited to customers building a compact suppressed bolt-action system. The short host helps offset the additional overall length created when a suppressor is installed.
CM offers both 1:3 and 1:5 twist options. With an 8-inch barrel, projectile construction, ammunition and velocity become particularly important, so the barrel should be configured around the load the firearm is intended to use.
A pistol configuration using a telescoping Tailhook brace is also available for customers who prefer that configuration.
CM7S Bolt Action
At the center of the 8.6 BLK SBR is the Chattahoochee Munitions CM7S action. The CM7S uses a Remington 700 footprint with a three-lug bolt and 60-degree throw in the same purpose-built action architecture used throughout our bolt-action firearm family.
- Remington 700 footprint
- Three-lug bolt design
- 60-degree bolt throw
- M16-style extractor
- One-piece .718″ bolt body
- Wire EDM raceways
- Pinned 20 MOA Picatinny rail
- Large ejection port
- Lightweight action-body cutout
- .062″ firing pin
- Integrated .300″ recoil lug
- Tool-less fire-control removal
- Accepts Remington 700-style triggers
- 1-1/16″-16 barrel thread
- Side bolt-stop release
- Oversized bolt knob
- Spiral-fluted bolt
- Full PVD coating
- Action weight: 25 oz
The three-lug design and short 60-degree bolt lift complement the compact dimensions of the 8-inch firearm while retaining the familiar Remington 700 footprint.
8″ Mos-Tek 8.6 Blackout Barrel
This 8.6 BLK SBR uses an 8-inch Mos-Tek premium bolt-action barrel manufactured from 416R stainless steel with 5R rifling.
- 8″ barrel length
- 416R stainless steel
- 5R rifling
- Choice of 1:3 or 1:5 twist
- Shouldered crown
- 5/8×24 muzzle threads
- Remage barrel-nut mounting system
- E100 Blackout Cerakote
CM offers both twist rates because projectile construction, length, weight, ammunition and velocity all influence stabilization. Rather than treating either twist as universally correct for 8.6 Blackout, we configure the barrel around the intended ammunition and application.
For a broader discussion of CM testing with barrel length, projectile weight, twist rate and suppression, see our 8.6 Blackout Subsonic Guide.
Why an 8″ 8.6 BLK SBR?
The primary advantage of the 8-inch configuration is reduced overall length. The resulting 8.6 BLK SBR measures approximately 20.50 inches at its shortest adjustment and weighs just 5 lb 12 oz.
That reduction becomes particularly useful when a suppressor is added. Starting with an 8-inch barrel helps offset the additional length of the suppressor and keeps the complete system shorter than a conventional rifle-length host.
There is a deliberate tradeoff. CM testing with subsonic 8.6 Blackout loads has shown approximately 12 to 12.5 inches to be a particularly useful barrel-length range for powder utilization in the loads we have evaluated. The 8-inch configuration instead prioritizes minimum overall length. Customers choosing between the two should consider barrel length, ammunition, projectile, twist rate and suppressor together.
TriggerTech Remington 700 Primary Trigger
The CM7S 8.6 BLK SBR is equipped with a TriggerTech Remington 700 Primary trigger, available in flat or curved configurations.
The Primary provides an adjustable pull-weight range of approximately 1.5 to 4.0 pounds. Because the CM7S accepts compatible Remington 700-style triggers, customers also retain additional trigger options if their requirements change.
CM7 Billet Chassis | Black Tungsten
The CM7 chassis is machined from billet aluminum and finished in Black Tungsten Cerakote. It provides a compact foundation for the CM7S while incorporating the magazine, accessory and rear-interface features used throughout the chassis-based CM7S family.
- Flared AICS-pattern magazine well
- Ambidextrous magazine release
- Large trigger guard for gloved operation
- Machined billet-aluminum construction
- Modular rear adapter system
- M-LOK compatible
- Full-length bottom ARCA rail
- Dual integrated QD sling sockets
- Compatible with AR-15 pistol grips without integrated dovetails
The firearm also includes the CM Precision Vertical Crossover Grip, developed in collaboration with MK Machining.
Telescoping SBR Stock
In its SBR configuration, the CM7S uses a telescoping butt pad assembly with an adjustable cheek riser. Combined with the 8-inch barrel, the telescoping rear assembly allows the firearm to remain exceptionally compact while retaining an adjustable shoulder-stock configuration.
The Black Tungsten chassis and black furniture distinguish this model visually while retaining the same CM7S mechanical architecture used throughout the 8.6 Blackout lineup.
SBR or Pistol Configuration
The primary configuration of this product is the 8.6 BLK SBR with a telescoping shoulder stock and adjustable cheek riser. Customers may alternatively select a pistol configuration equipped with a telescoping Tailhook brace.
The shoulder-stock configuration is an NFA-regulated short-barreled rifle and must be transferred and possessed in accordance with applicable federal, state and local requirements.
Vetted AICS Magazine System
The CM7S uses an AICS-pattern magazine architecture. CM uses a vetted magazine configuration with its 8.6 Blackout bolt-action firearms so magazine compatibility is incorporated into the complete firearm system rather than left to customer experimentation.
Additional CM 8.6 Blackout Magazines are available for the bolt-action platform.
Compact Suppressed Bolt-Action System
The 8-inch barrel gives this CM7S a different role from our 12-inch and 16-inch configurations. The 8.6 BLK SBR prioritizes keeping the complete firearm as short and light as practical, especially when additional muzzle length will be added by a suppressor.
The bolt-action operating system also avoids the gas-system and buffer-system variables associated with cycling a semi-automatic firearm. Ammunition selection can therefore be approached independently from the requirements of a semi-automatic operating cycle.
The barrel terminates in standard 5/8×24 muzzle threads for appropriately configured muzzle devices and suppressor mounting systems. Compatibility should always be verified for the specific suppressor, ammunition and firearm configuration.
Choosing Between 1:3 and 1:5 Twist
CM has been building 8.6 Blackout firearms since the cartridge’s early introduction, before SAAMI standardization. Our experience has reinforced that twist selection should be considered alongside projectile design, weight, velocity and barrel length.
Across our longer 12- to 12.5-inch configurations, 1:5 has generally performed well with projectiles around 300 grains or less, while 1:3 has generally been better suited to heavy subsonic projectiles around 323 grains and above. An 8-inch barrel changes the velocity environment, making selection around the actual intended ammunition especially important.
CM therefore offers both twist options rather than presenting either one as universally correct.
For customers prioritizing minimum overall size in a stocked bolt-action configuration, the 8.6 BLK SBR combines an 8-inch barrel, CM7S action, telescoping stock and billet chassis into an exceptionally compact 8.6 Blackout package.
To compare this SBR with our other CM7S barrel lengths, pistol configurations, CM10 AR10 platforms, barreled actions and supporting components, visit Area 8.6.
CM7S 8.6 BLK SBR Specifications
| Platform | CM7S Bolt Action |
|---|---|
| Caliber | 8.6 Blackout |
| Primary Configuration | Short-Barreled Rifle (SBR) |
| Optional Configuration | Pistol |
| Barrel Length | 8″ |
| Barrel Manufacturer | Mos-Tek |
| Barrel Material | 416R Stainless Steel |
| Rifling | 5R |
| Twist Rate | 1:3 or 1:5 |
| Muzzle Threads | 5/8×24 |
| Trigger | TriggerTech Remington 700 Primary |
| Magazine Pattern | AICS |
| Chassis Finish | Black Tungsten Cerakote |
| Furniture | Black |
| SBR Rear Configuration | Telescoping Butt Pad with Adjustable Cheek Riser |
| Pistol Rear Configuration | Telescoping Tailhook Brace with Adjustable Cheek Riser |
| Weight | 5 lb 12 oz |
| Overall Length | 20.50″ – 28.0″ |
| Length of Pull | 6.0″ – 13.5″ |
8.6 BLK SBR FAQ
How compact is the CM7S 8″ SBR?
The 8-inch CM7S weighs 5 lb 12 oz and has an adjustable overall length of approximately 20.50 to 28.0 inches.
Can I order the 8″ CM7S as a pistol instead?
Yes. The alternate pistol configuration uses a telescoping Tailhook brace with an adjustable cheek riser. The primary configuration presented on this page is the shoulder-stock SBR.
Why choose an 8″ barrel?
The 8-inch configuration prioritizes minimum overall length. This is particularly useful when a suppressor will add length to the complete firearm system.
Should I choose 1:3 or 1:5 twist?
The appropriate twist depends on projectile construction, weight, ammunition, velocity and barrel length. CM offers both options so the firearm can be configured around the intended load.
Can the 8.6 BLK SBR be suppressed?
Yes. The barrel uses 5/8×24 muzzle threads for compatible muzzle devices and suppressor mounting systems. Compatibility should be verified for the specific suppressor, ammunition and firearm configuration.
What magazine does the CM7S use?
The CM7S uses an AICS-pattern magazine architecture. CM offers a vetted 8.6 Blackout Magazine for the bolt-action platform.
Where can I compare other CM 8.6 Blackout firearms?
Visit Area 8.6 to compare CM7S bolt actions, CM10 AR10 platforms, pistol and SBR configurations, barreled actions and supporting components.
NFA NOTICE: The shoulder-stock configuration shown as the primary configuration on this page is an NFA-regulated short-barreled rifle and is subject to applicable federal, state and local requirements.
russ.joyc@gmail.com (verified owner) –
Beyond happy with this rifle and the customer service from Matt! It shipped the same week ordered and each update about the firearm was conveyed to me and provided with a tracking number once shipped.
This is my first firearm from Chattahoochee Munitions and everything about this rifle looks and feels high quality. It had no scuffs, scratches, rough edges or anything to complain about out the box. It was packaged securely double boxed in a cardboard box with a lot of felt/ padding to prevent it from sliding and being impact resistant.
I bought the pistol/tail hook assembly brace. Tried to find wobble in it, none whatso ever. There are three adjustable lengths, I’ve tried two different scopes on it, first a LPVO which worked great with the 2nd length (middle) position when shouldering and using the cheek rest. And now I’ve mounted a thermal which works great on the 1st (shortest) length when shouldering for eye relief. I have shot 50 rounds through this rifle, 25 Gorilla 342gr Porkshredder expanding subsonic rounds, and 25 Gorilla 285gr Fracturing subsonic rounds. While sighting in the LPVO and Thermal I had 3/5 bullets land basically in the same hole, with about 1 MOA at 50 yds with the 285gr bullets! These bullets are not made for accuracy which is stated on Gorillas website. The pork shredder shot as advertised about 2 MOA 50 and 100yds. I am sure with better non hollow point ammo types the accuracy of this 12in barrel could be sub MOA easily.
The trigger is another phenomenal piece to this firearm, it is advertised as 8-20oz. I have not measured it, but I can only assume its currently 8oz. My first few times firing the firearm I was amazed just how quickly the trigger breaks, I tested the trigger for drop safety, smacking the tail hook and other places of the firearm randomly to simulate a drop of the gun and it never dry fired.
It has a big trigger guard making it easy to shoot with the average hunting glove. I’ve been using the 10 round Pmag that came with the firearm in the box, it fits right in, no snags or resistance and pops right out. Mag release is the outer edge of the trigger guard, no problems with it either, easy to unload with hunting gloves on as well.
It was stated in the manual, the gun was test fired 3 times, and was lubed to a degree, while unboxing the firearm I found the three spent brass casings and saw upon initial inspection of the gun, light lube where it was needed. Some guns I’ve had tight bolts when trying to extract unfired or even spent casings. No problems extracting with this firearm, even when not “broken in” yet, everything was smooth out out the box even with no extra lubrication applied yet.
When cycling the bolt to chamber another round I would have binds if I did it really slowly, I was trying to protect the tip of the big hollow point bullet by feeding it slowly but it would seem to jam up a little bit and just a nudge of the bolt would send it into the chamber, when racking the bolt back and fourth at any normal pace it would have no problems extracting or feeding. This could be ammo specific on Gorillas end, after slamming the bolt forward several times with the two different bullets there wasn’t any deformation which I could see.
I look forward to buying a suppressor for this firearm and unlocking its full potential with subsonic 8.6 BLK.
Matt was great on fixing an issue I made ordering my firearm very quickly even after hours with no hassle. For the price I don’t think it can get any better for a SBR/ Bolt Action Pistol it is extremely high quality from my experience. And would recommend this to anyone in the market for a similar type of firearm!
admin (store manager) –
Thank you Russ. We appreciate your feedback. Enjoy it!