CMMG Revolution and M300 Rifles

CMMG announced several new products at the 2012 SHOT Show.  Aaron caught up with them and took a look at the new CMMG Revolution and CMMG M300 rifles.

Being from Missouri I had to stop by and check out the latest from CMMG.  At the CMMG booth, I talked with Larry Wayland who sells their rifles through his retail store, and works closely with the CMMG staff.

The explosion of the .300 Blackout cartridge focused my attention to the CMMG M300, but while there Larry also showed me a very interesting new development that CMMG has been playing with. It’s called the Revolution model upper receiver and hand guard. This is an innovative AR-platform concept and CMMG has the patents. In addition to the .300 Blackout rifles coming out, the Revolution system is offered on their standard 5.56mm rifles as well.

CMMG Revolution


This new creation from CMMG allows for an ambidextrous upper receiver. Not in the traditional sense, but instead the receiver is milled to allow the same receiver to service a right-handed or a left-handed shooter. This innovation cuts an ejection port on both sides of the receiver. So the selected shooting configuration (right/left handed) has a bolt-on plate containing the ejection port and forward assist knob. The other side of the receiver has a bolted on plate covering that ejection port.

If the shooter desires to change the rifle to the off-hand variety all they have to do is simply unscrew the ejection port plate and switch sides with the off-hand version. The opposite plate covering the back side should be universal.

Larry told me that CMMG plans on milling their bolts in the future to have ambidextrous features so the same bolt can be used for both configurations. Currently the Revolution uppers only have a plate that already has the forward assist knob attached, requiring a left-handed plate and knob combination for left-handed shooters.

CMMG Revolution

Future CMMG plans involve making their Revolution uppers with ambidextrous forward assist levers already milled into the upper. Levers on both sides of the receiver. That way on/off ejection port plate could be made universal, and along with the backside plate, would be the only required interchangeable parts. The new bolts would already be milled to accept either side controls, so you really have a very quick and easy transition from right to left-handed shooting.

Some may not see a real use for this innovation, but I’m thinking about government and law enforcement agencies that issue weapons. Those weapons might be issued to multiple persons over time, not all of whom are right handed shooters. This would be a relatively inexpensive way to “fix” a rifle to a left-handed configuration without purchasing a whole new rifle.

CMMG Revolution

Another application would be a family that has both right and left-handed shooters. Again, the Revolution upper would allow the family to shoot the same rifle with a few quick adjustments, and not break the family budget by buying multiple rifles.

From what I’ve seen I think CMMG got the name right – this truly is a “revolutionary” design concept that jumps way outside the normal thinking box.


The Revolution Rail System is a modular format that is designed as a free- floating rail system. Larry told me that the connections are very simple, and the rail fits nice and snug to the Revolution upper. It is possible to attach the Revolution Rail System to a standard AR-upper receiver, and in that case the Revolution Rail will slide partially over the end of the upper when connected. The fit appears very tight and well milled.

CMMG Revolution

The Revolution Rail System offers its own handguard that bolts directly to the rail and has optional attachment points to the rail, leaving Picatinny rail sections to support lights and other accessories. The Revolution handguard wraps underneath the rail and is also bolted to the other side. It appears that the shooter can also take the handguard off completely while leaving the Revolution rail attached, so they can add their preferred accessories as they see fit.


CMMG offers the M300, chambered in the new .300 Blackout caliber, with three different barrel lengths – 8.5”, 12.5”, and 16”. Here are the common features of all the 300 AAC Blackout rifles:

4140 Chrome-Moly Steel barrel WASP treated barrel (chamber and bore) 5/8-24 Muzzle thread 1:8 twist A2 flash hider Forged, T-Mark upper receivers with M4 feed ramps Forged, lower receivers are RDIAS/RLL compatible Mil-Spec takedown pins & FCG pins Mil-Spec 6-position collapsible carbine stock.

CMMG Revolution

There is one version that has the Revolution upper and rail system innovations. Another has a standard AR-platform upper with a Revolution rail system. Those come with either a medium handguard, or a carbine length handguard. The other versions come with standard AR-platform set-ups.

The selections are available as gas impingement systems currently, but can accept the gas piston systems. If the gas impingement carbine is selected, CMMG includes the A2 front sight. If the gas impingement medium rail option is desired, the impingement capture tube is still attached to the barrel but is hidden under the medium Revolution or standard mid-length rail. No A2 front sight is provided in the mid-length rail configuration.

If you’re not impressed with the Revolution hardware CMMG offers the .300 Blackout with various combinations of other hardware. There are options of an M4, Mid-length 4 rail, or Revolution handguard. If you’re looking to simply switch out uppers, CMMG offers complete uppers (with barrel and handguard) in the various barrel lengths.

CMMG is looking at an MSRP of around $1300 for the M300 with the Revolution upper and rail system. Prices for the other versions are being set now and should be out in the next few weeks.

The Revolution rail system handguard by itself is expected to go for about $120.

CMMG Revolution

By Aaron

Aaron is a sergeant with a midwestern police department, where he serves as a trainer, supervisor and SWAT sniper. In addition to his broad tactical knowledge, Aaron is an experienced hunter using bow and both modern and blackpowder firearms.