DR Exclusive First Look!: SCAR Who? Meet the Colt Modular Carbine (CMC) Model CM901 Multi-Caliber 7.62mm NATO Battle Rifle / 5.56mm NATO Assault Rifle for U.S. Military Special Operations Forces (SOF) and General Infantry Forces (GIF). DefenseReview (DR) Reports (Photos and Video!)

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By David Crane
defrev (at) gmail (dot) com

All photos and video clips contained in this article were shot by DefenseReview.com (DR), and are copyrighted. DefenseReview.com owns the copyright on these photos and video clips. The embedded photos and video clips were shot with a Canon PowerShot S90 10-megapixel digital camera (still camera with video capability).

October 6, 2010

On Thursday, September 9, 2010, Defense Review visited Colt Defense LLC in Hartford, Connecticut to see, handle, photograph, videotape, and test-fire a gun I’d only heard about in excited whispers and hushed tones from professional contacts of mine, a ballistic specter that had already, sight unseen, excited the imaginations of all the tactical gun cognoscenti who were already aware of its existence. The very-short-notice invite had come the week before in the form of an email message from a high-ranking Colt Defense executive. The message was short and concise. It read: “David – Would you be interested in our flying you out here next Wednesday to meet with us next Thursday to see the CM901 and write an article on it?” My response was even shorter and more concise: “Sure! Absolutely.”

The following week, after moving some prior engagements around, I was on a plane on Sept. 8th flying out to experience the Colt Modular Carbine (CMC) Model CM901 modular, multi-caliber battle rifle/assault rifle/carbine/SBR (Short Barreled Rifle) for myself. “Modular” and “multi-caliber” are actually understatements, since the CM901 is, hands, down, the most versatile battle rifle/assault rifle we’ve ever seen in both respects. The heart of this versatility lies in the combination of the patent-pending AR (AR-10/AR-15)-format “universal” multi-caliber lower receiver and conversion system and Colt Defense’s various AR operating systems and uppers, which allows the end-user to configure the gun in so many mission-specific ways, it’s almost mind-boggling. The CM901 provides a truly sumptuous feast of versatility with regard to configuration options. Let’s get right to the high points:

1) The Colt CM901 Modular Carbine is a select-fire AR (AR-10/AR-15)-platform weapon, so it will immediately look, feel, handle, and shoot in a way that’s immediately familiar to all military end-users, including general infantry personnel. It also benefits from the AR platform’s now legendary ergonomics/usernomics.

2) The CM901 multi-caliber battle carbine can be configured in any/every caliber between 7.62x51mm NATO (7.62mm NATO)/.308 Win. and 5.56x45mm NATO (5.56mm NATO)/.223 Rem., including 6.8 SPC (6.8x43mm SPC) and 6.5 Grendel, depending on what U.S. military end-users require. To switch from 7.62mm to 5.56mm, just push out the two receiver pins, take the 7.62x51mm upper module off, slap the 5.56mm upper module on, push the two receiver pins back in, and you’re good to go.

3) The CM901 universal lower receiver will accept any/all legacy MILSPEC 5.56mm NATO AR rifle/carbine/SBR upper receivers already in the U.S. military inventory, including the, Colt M4/M4A1 Carbine 14.5″ AR carbine , M4 Commando 11.5″ AR SBR, MK18/CQBR (Close Quarters Battle Receiver) 10.3″ AR SBR, and M16A3/A4 20″ DGI rifle uppers. The CM901 lower will also accept the Colt LE6940 16″ monolithic upper and Colt LE6920 16″ M4/M4A1 Carbine-type uppers. Thus, 5.56mm barrel length is determined by whatever AR upper you want to use. Defense Review test-fired the Colt CM901 7.62mm upper sporting a 16″ barrel, but it’s DR’s understanding at present that 13″, 18″, and 20″ barrels will also be available per customer request (unconfirmed/unverified).

4) While the CM901 7.62mm upper receiver is a monolithic upper/rail format with a direct gas impingement (DGI) operating system, the CM901 can utilize just about any 5.56mm rifle/carbine/SBR operating system that Colt manufactures, including the Colt M4/M4A1 DGI system, Colt APC (Advanced Piston Carbine)articulating-link gas piston/op-rod (operating rod) system, Colt AHC (Advanced Hybrid Carbine) DGI/piston-driven hybrid system, and Colt ACC-M (Advanced Colt Carbine-Monolithic) monolithic DGI upper. Defense Review does not yet know whether or not the CM901 lower can be configured to work with the Colt SCW (Sub-Compact Weapon) SBR upper, since the SCW utilizes a special short buffer system and buffer tube, which allows it to utilize a folding/telescoping buttstock.

5) The CM901 sports fully ambidextrous controls a.k.a. “full ambi controls”, including ambidextrous safety/selector switch, bolt catch hold-open/release lever, and magazine release button.

6) The CM901 when configured for .308 Win utilizes the MagPul 20LR 7.62 magazine. The weapon will also accept the SR25/M100 7.62mm magazine. The weapon when configured for 5.56mm will accept all “MILSPEC” 5.56mm magazines.

7) Being an AR, the CM901 can utilize some aftermarket tactical AR rifle parts and accessories, like telescoping/retractable buttstocks, and trigger/hammer groups. Colt Defense had both Vltor IMOD and Vltor EMOD stocks for the CM901 prototype on hand, while I was there, but you can stick a MagPul CTR (Compact/Type Restricted) stock or LMT SOPMOD/SOCOM/Crane NSW stock on there, if you’d like.Editor’s Note: Defense Review likes all three buttstocks (Vltor IMOD, MagPul CTR, and LMT SOPMOD).

The CM901 will provide the military end-user with a select-fire AR platform weapon in any caliber between 5.56mm and 7.62x51mm, allowing him to use any “MILSPEC” 5.56mm AR upper receiver he wants, also allowing him to use any 5.56mm AR operating system Colt Defense offers, and lets him choose his barrel length. Colt Defense is even in the process of developing their articulating link piston and DGI/piston hybrid operating systems for the 7.62x51mm CM901 upper receiver module.

The CM901 Upper Receiver Modularity concept: just change out your upper receiver assembly to re-configure the weapon for the mission, without having to re-zero your weapon and you’re ready to go. Examples of upper receiver configurations users could have are:

– MK18/M4 CQBR 10” upper equipped with a EOTech EXPS3-2 HWS (Holographic Weapon Sight), Aimpoint Micro T-1, Aimpoint CompM4, or FERFRANS FAS (Fast Acquisition Sight) combat optic.,
– Colt M4/M4A1 Carbine 14.5” upper equipped with a ELCAN SpecterDR 1-4x or Trijicon ACOG (Advanced Combat Optical Gunsight).,
– MK12 Mod 0/1 SPR (Special Purpose Rifle) 18” upper equipped with a Schmidt & Bender Short Dot Scope or Trijicon Accupoint Scope., and
– CM901 7.62mm carbine/rifle upper equipped with a Nightforce NXS 2.5-10×32 Compact or Leupold Mark 4 3.5-10x40mm ER/T M5 Front Focal Riflescope.

Military operators are already used to swapping out AR uppers with optics pre-mounted and zero’d. They like this system, and they trust it–and it’s already battle-proven.

Defense Review spoke with CTT Solutions/Grey Group Training tactical instructor, retired U.S. Army Special Forces (SF) assaulter/operator, and Defense Review contributor Mike Pannone a few days ago about the CM901, and asked him his opinion about it vs. the FN SCAR weapons, assuming FN fully develops the SCAR “common receiver”. Mike prefers the AR rifle system’s upper receiver modularity to the FN SCAR quick-change barrel system/”trigger module” combo, and he had this to say (or, in this case, write) about a barrel change/lower receiver module system (SCAR) vs. modular upper receiver change system (CM901):

People often confuse quick change with modularity when it comes to weapons systems. They are in fact completely different concepts in nearly every regard.
For the sake of discussion let’s talk about quick-change barrels vs. modular upper receivers (AR/M-4 type platform).

First, the definition: quick-change means that parts of an existing weapons system can be replaced with the same replacement part (think fixture point, not cosmetics or barrel length) in a relatively rapid manner with minimal or no tools. I emphasize “relatively” because that is subject to end user specifications. Quick change can be 5 minutes (LMT MRP barrel) or 10 seconds (M249 barrel), so it’s relative.

Modular means a family of parts and accessories will fit on any system that uses a standardized mounting platform. The AR family of weapons and the [Mil-Std-1913] Picatinny rail are the best example of modularity. The AR system, as well, is in its 2 primary components a modular system; push two pins and you can swap complete uppers, even between nearly all manufacturers.

Modularity by default is quick-change but quick change is not always modular.

I challenged Mr. Pannone with the following:


Couldn’t FNH argue that, once they have a “common receiver” (upper receiver) for 7.62 and 5.56, their quick-change barrel system and swappable trigger module/lower receiver module together make a modular system?

Not the barrel by itself, but the combination of the two. Just looking at every angle.

To which he countered with:

It will make them quick change within their system as well as limited modularity within the system. It is not modular in the bigger sense that there are many different vendors offering a menu of replacement parts that are swappable. By the letter f the definition it would be modular, but [only] in the most limited sense, and only within their own manufacturing capacities, since no companies that I know of make replacement parts [for the SCAR weapons].

If you extrapolate it out, everything, in a sense, is modular in its own right.

In industrial design, modularity refers to an engineering technique that builds larger systems by combining smaller subsystems.

Defense Review contributor Chen Lee (a.k.a. “SMGLee) commented on the combat advantages/attributes of the Colt CM901 modular/multi-caliber weapons platform:

The capability provided by the CM901 gives an additional dimension to [military] operators. No longer will a warfighter get stuck running a DMR [Designated Marksman Rifle] in an urban warfare environment, where the platform might not suit that particular moment of combat. Those days of a sniper carrying a rifle in a backpack, while fighting his way into position with a handier weapon, are a thing of the past with the advent of the CM901. Today, a warfighter can have his cake and eat it too, fighting with a MK18 Mod1 on a CM901 lower while the .308-based CM901 is carried in a padded backpack. When the occasion arises, the operator can change out the 5.56mm CQB-R and instantly go to a .308 rifle [CM901 7.62mm upper] for the counter sniper role, or any situation that requires a designated marksman.

The only downfall I see would be the logistics of keeping two separate calibers within one shooter’s loadout. But with 5.56 [mags] carried on the vest, the .308 magazines could be carried in a pack since the shooter is already dropping the backpack in order to access the .308 platform.

The CM901 will provide added fighting capability to [military] operators in today’s ever-changing battlefield.

Colt Defense Executive Vice President (EVP) and Chief Operating Officer (COO) Maj. Gen. James R. Battaglini USMC (Ret.) issued the following statement on the CM901 to DefenseReview:

Colt Defense’s approach to weapon design is to determine the warfighter requirement and then to provide a solution. Our primary customer is the US military, not the commercial market. Colt’s focus is the warfighter; our largest customer is the US Army; and, we design and manufacture to strict military specifications. Despite efforts by individuals to deride the M4 Carbine in order to promote other products, many which are commercial off the shelf, the US Army and Soldiers have been more than satisfied with the performance of the M4 Carbine in combat over the past 7 years in Iraq.

As US forces have now transitioned their focus of effort to the war in Afghanistan and its combat conditions and threat, warfighters are more adamant in seeking varying calibers and a higher level of modularity in their individual weapons to meet mission needs. With the performance of the M4 Carbine and M16 Rifle as the proven standard for the 5.56mm individual weapon, Colt’s approach has been to provide a simple and cost effective solution to meet evolving warfighter demands.

Colt’s CM901 is designed as a multi-caliber, modular capability with one lower receiver configurable to different calibers and barrel lengths for different missions. With its universal lower receiver based on the 7.62 mm round and the ergonomics of the M4 and M16, the lower receiver is also compatible with the upper receivers and bolt carrier assemblies of all existing Colt weapons in the military inventory and its newly developed weapons and alternative operating systems from 7.62mm to 5.56mm. Colt has kept its solution simple, operationally and cost effective, and easily adaptable for the warfighter and the support base.

Test-Firing Session

While Defense Review was at Colt Defense LLC, we had the opportunity to fire the CM901 in both the 7.62x51mm and 5.56mm configurations on both semi-auto and full-auto at Colt’s indoor test range. Colt Product Requirements Manager Chuck Olsen and I put a few hundred rounds down range between us, without experiencing any malfunctions. Chuck shot with a bit more abandon than I did, as I was concerned about putting bullet holes in the walls and ceiling, especially while firing full-auto strings. The test CM901 7.62mm upper and universal lower being prototypes, I’d expected the weapon to hiccup a little bit during the firing test, but nope, it didn’t. It ran like a charm. The CM901 universal lower receiver/caliber conversion system works. It really works. It works like gangbusters–at least under range conditions. Let’s face it, test firing a weapon system at a clean, dry range for only a few hundred rounds isn’t exactly a proper test of a military small arm. Firearms designed specifically for military combat must prove reliable, durable, and accurate under adverse combat conditions at high round count. They have to be tested for tens or even hundreds of thousands of rounds in mud, sand, rain, snow, dirt, you name it, and keep going bang…every time. DR didn’t have the opportunity to test the CM901’s accuracy in either caliber configuration, but it’s an AR, and ARs are famously accurate, assuming they’re built right.

We only test-fired the CM901 with DGI (direct gas impingement) operating systems in 7.62mm and 5.56mm configurations. It should perhaps be noted that the LMT .308 MWS (Modular Weapons System) DGI 7.62mm battle rifle/marksman rifle recently beat out the gas piston/op-rod-driven HK417 and SCAR-H rifles to win a British Army contract. The British military has designated it the L129A1 rifle/carbine. It’s DefenseReview’s theory that direct-gas-impingement (select-fire and semi-auto-only) rifles chambered in 7.62mm NATO/.308 Win. may actually enjoy a durability and accuracy advantage over gas piston/op-rod (operating rod) 7.62mm rifles, due DGI’s lack of direct mechanical impact on the gas key/bolt carrier key/strike plate/tombstone and lack of a relatively heavy mechanical reciprocating mechanism (piston/op-rod) above the bore line. It’s just a theory at this point, though.

We didn’t test the CM901 for accuracy, but it’s an AR, and it’s made by Colt Defense. We’d like to perform an accuracy and reliability test on an outdoor range, as a follow-up, at some point.

Whether or not the Colt Modular Carbine Model CM901 ends up being adopted by the military will depend on two things: 1) Colt developing it successfully and 2) the U.S. military small arms procurement folks preferring it to other weapon systems being evaluated. If Colt is successful though, the U.S. military will have a second modern 7.62mm battle rifle/carbine/SBR option at their disposal, in AR format. In Defense Review’s opinion, that’s a nice choice to have. The question is, will civilian tactical shooters get the same choice? Will Colt make the CM901 available to the civilian tactical shooting sector of the commercial market? Defense Review certainly hopes so. They’d better.

It’s DR’s opinion that if the the Colt CM901 ends up meeting (or exceeding) all U.S. military requirements, it represents the most important development in tactical AR rifles in, well…the history of ARs! With the CM901 modular/multi-caliber weapons system, Colt has essentially taken the military/tactical AR weapons platform taken to its ultimate logical conclusion, the ultimate evolution of the AR platform, if you will—and we want one. We’ll settle for the semi-auto-only version.

But what do you think? We’re interested in our readers’ thoughts and perspectives, so please feel free to comment, below.

The following are some Colt CM901 specs:

Weapon Type CM901, 16″ BBL, BUIS, IMOD Stock CM901, 16″ BBL, BUIS, EMOD Stock CM901, w/M4A1 Upper Receiver, RAS Handguards, IMOD Stock CM901, w/LE6940 One-Piece Upper Receiver, IMOD Stock CM901, w/CQB One-Piece Upper Receiver, IMOD Stock
Barrel Length 16″ 16″ 14.5″ 16″ 10.3″
Weight W/O magazine 8 LBS 13 OZ 9 LBS 1 OZ 7 LBS 6.5 OZ 7 LBS 6 OZ 6 LBS 12.5 OZ
Extended Length 37.25″ 38.25″ 34.0″ 35.875″ 29.75″
Collapsed Length 34.0″ 35.0″ 30.75″ 32.625″ 26.5″

The following information comes from the Colt CM901 data sheet/fact sheet:

Colt Modular Carbine (CMC) Model CM901

General Description:

The Colt Modular Carbine (CMC) Colt Model (CM901) is a User-level, mission configured, lightweight modular, multi-caliber, weapon system. The system utilizes a one-piece upper receiver and is a multi-caliber, multi-operating system carbine/rifle; it is magazine fed and capable of firing in both automatic and semi-automatic modes. Utilizing a revolutionary new lower receiver and bolt carrier design the CM901 provides unmatched modularity in carbine and rifle design, allowing the warfighter to quickly reconfigure the weapon system to meet multiple mission requirements.


The Colt CM901 can change calibers from 5.56mm up to and including 7.62 x 51mm NATO, by changing the upper receiver group. By simply disengaging the takedown and pivot pins (No Tools, Gunsmith, or Gauges Required), the user can quickly change from a 5.56mm Close Quarters Battle (CQB) short barrel configuration to a full length 7.62 x 51mm Extended Range Carbine (ERC) configuration in seconds without the need to re-zero mounted sights. The CMC weapon system is the ONLY SYSTEM to offer this user-level truly modular configuration capability. The CMC system all but eliminates critical mission time loss and key personnel requirements to execute weapon configuration changes. This self-contained design concept protects critical components of the operating system and provides uninterrupted operability in all environments. The CMC is the ONLY “Single Serial Number Weapon System” that can be reconfigured, at the commander’s discretion, into multiple carbine/caliber configurations without special tools. This same modular capability not only applies to the caliber, but also to the operating system, which can be configured for gas impingement, piston (Colt APC), or hybrid gas/piston (Colt AHC) operating systems. All of these modular attributes are now available at the unit level without sacrificing the battle proven ergonomics and reliability warfighters have come to expect from Colt Defense LLC products.

Colt CM901 7.62x51mm Carbine Features:

• Universal Lower Receiver-
– Unique design enables use of multiple calibers from 5.56 x 45mm up to and including 7.62 x 51mm available within a single serialized receiver
– Compatible with legacy M4/M16 magazines, and upper receiver/barrel assemblies with multiple barrel lengths
– Built in ambidextrous bolt catch, magazine catch, and selector
– Compatible with M4/M16 Trigger mechanisms
– Configurable with new Colt operating systems and designs

• Modular One-Piece Upper Receiver-
– Forged 7075-T6 Aluminum
– Steel inserts in critical wear areas provide higher level of reliability and extended service life of upper receiver
– Integral continuous MIL-STD-1913 rail extends the length of the receiver, providing rigidity, and uninterrupted mounting space
– Rigid MIL-STD-1913 rails at the 3 and 9 o’clock positions
– Removable Lower Rail at the 6 o’clock position allows for attachment of accessories like the forward grip, M203 and M320 grenade launchers, and other mission essential ancillary devices

• Barrel
Free floating barrel, 4 groove, 1 in 12” twist rate
Available in optional barrel lengths of 13”, 16, & 18”
Suppression Capable- Utilizes the SEI Vortex Compensator

• Bolt
– New advanced material providing extended service life of the bolt and reduces life-cycle costs

• Magazine
New Robust Polymer Construction
Compatible with the M110, MK11, and SR25 metal magazines

• Adjustable Folding Front Sight
Offers mounting of multiple sights and ancillary devices without obstruction of standard front sight post

• Mil-Spec Hard Coat Anodize-
– Available in multiple camouflage colors and patterns

Colt CM901 Benefits:

– Modular operating system

• Universal Lower Receiver permits the individual user — with no special tools — to convert a “single serialized lower receiver” into multiple caliber, barrel-length, and operating system configurations

• Eliminates need for non-standard weapon systems, and training for those systems, that are currently employed in the Battlespace in order to support Warfighter Multi-Caliber requirements to meet changing mission needs

• Designed to accept all legacy M4/M16 Colt upper receiver assemblies

• Designed for ease of disassembly, maintenance, and reassembly

– Stable platform for mounting optics and other ancillary devices to enhance mission performance and capability

• Reliable Zero Retention and Zero Repeatability provided by the rigid one-piece upper receiver design

• One-Piece Upper Receiver design reduces the number of components, increases rigidity, and provides system weight savings

– Improved Durability and Reliability

• Hardened Steel inserts in high wear areas of the upper receiver provides extended life

• New Advanced Bolt material enhances system life

• New Extractor and Extractor Spring enhances system reliability and durability

– Improved Accuracy

• Free Floating Barrel system incorporates a new barrel extension to upper receiver interface to improve accuracy and hit probability

– Ergonomically compatible with the M4 Carbine

• Very low Doctrine, Organization, Training, Material, Leadership, Personnel, Facilities (DOTMLPF) footprint in fielding to the Warfighter

• No need to re-train Warfighters on new system, only familiarize with upgrades

– Quality- ISO 9001:2008

– Made in the U.S.A and built to U.S. MIL-SPEC”

Company Contact Info:

Colt Defense LLC
547 New Park Ave
West Hartford, CT, 06110
800-241-2485 Toll Free
860-232-4489 Office
860-244-1442 Fax
http://www.colt.com Website

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DR Exclusive First Look!: SCAR Who? Meet the Colt Modular Carbine (CMC) Model CM901 Multi-Caliber 7.62mm NATO Battle Rifle / 5.56mm NATO Assault Rifle for U.S. Military Special Operations Forces (SOF) and General Infantry Forces (GIF). DefenseReview (DR) Reports (Photos and Video!) by

About David Crane

David Crane started publishing online in 2001. Since that time, governments, military organizations, Special Operators (i.e. professional trigger pullers), agencies, and civilian tactical shooters the world over have come to depend on Defense Review as the authoritative source of news and information on "the latest and greatest" in the field of military defense and tactical technology and hardware, including tactical firearms, ammunition, equipment, gear, and training.

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