Suppressor Company Offers An AR?—The AAC MPW in 300 BLK—Full Review

For more information, visit https://www.advanced-armament.com.

To purchase an AAC MPW on GunsAmerica.com, click this link: https://www.gunsamerica.com/Search.aspx?T=AAC%20MPW.

To purchase an AAC suppressor on GunsAmerica.com, click this link: https://www.gunsamerica.com/Search.aspx?T=AAC%20suppressor.

Today, everyone in the industry is aware of the 300 BLACKOUT cartridge. Indeed, firearms and ammunition in 300 BLK are readily available from most major manufacturers. However, many readers may have forgotten, or never heard, the origins of the cartridge. In 2009, it was announced that Remington was purchasing Advanced Armament Corporation, the hugely successful suppressor company. At that time, Remington left the former AAC team intact, to include founder and president, Kevin Brittingham. In September of 2010, I met with Kevin at a military conference. He pulled me off to the side and showed me the concept presentation for a new cartridge, the 300 AAC BLACKOUT. And that cartridge would lead to the development of the MPW we are reviewing here today.

SPECS

• Chambering: 300 BLK
• Barrel: 12.5 or 16 inches (9-inch variant discontinued)
• Weight: 6.8 pounds
• Stock: Collapsible
• Sights: None
• Action: Direct gas impingement
• Finish: Matte black
• MSRP: $1,599.95

Brittingham stated that the 300 AAC BLACKOUT cartridge was the result of a request for proposal (RFP) from a special mission unit within the United States military. The unit wanted a .30-caliber cartridge that would utilize the standard AR-pattern 5.56 magazines and bolts. The RFP also proposed both a sub-sonic round for use with a suppressor and a supersonic round. It was then that Robert Silvers, the Director of Research and Development for AAC, penned the following objectives for the new cartridge:

• Create a reliable and compact .30-caliber round for the AR platform
• The round would utilize existing 5.56 magazines and retain their full capacity
• Create a sub-sonic round that is optimized for sound and flash suppression
• Create a supersonic round that matches 7.63X39mm ballistics
• Provide the ability to penetrate barriers with a high-mass projectile
• Provide a lightweight, durable, and low recoiling upper receiver.

The end result is what is now known as the 300 AAC BLACKOUT. The 300 AAC BLACKOUT, or technically 7.62X35mm, was designed with the same rim dimensions and cartridge taper as the 5.56. This was a critical requirement in order to utilize the existing mil spec 5.56 bolt, and feed reliably from a standard 5.56 magazine. The configuration allows a standard M4 Carbine-style firearm to be converted to 300 AAC BLACKOUT by simply changing the barrel.

The key to making this project a success was Remington’s decision to develop the new cartridge under its own banner. This was key to success in both the civilian and potential military market. Remington submitted the new cartridge for SAAMI approval. With that approval, the 300 AAC BLACKOUT became a legitimate commercial cartridge. The final key to success came with the decision to allow other manufacturers to produce ammunition, firearms and components without any licensing agreements or royalties. This opened the door for the entire industry to become involved and take ownership of the new cartridge.

AAC immediately began producing complete upper receivers chambered in the new cartridge. The first group of these receivers went to government/military units, and reports were that the new cartridge performed well “down range.” In June of 2011, I was able to evaluate one of the first 9-inch SBR upper receivers. During the brief test, I came to understand what the excitement was all about. The versatility of the cartridge and the effectiveness of the subsonic ammunition were impressive.

As the market grew, AAC introduced an AR line chambered in 300 BLK.  The AAC MPW carbines were initially offered in a 16-inch barrel configuration as well as at that time 9- and then 12.5-inch NFA version. All MPWs have a direct impingement operating system. The rifles were an instant success and the AAC MPW carbine became one of the most sought after rifles in its class.

Part of the AAC marketing strategy was to offer the MPW with premium features and components. As to be expected, the upper and lower receivers are forged and machined to military specifications with standard controls. The MPW features the Knight’s Armament URX III rail. The URX III features a smooth tapered bottom and slides with a short section of rail at nine, three, and six o’clock. This significantly reduces the overall diameter compared to the original URX design. The smooth sides have three tapped holes that allow the user to add attachment points. My current test rifle was equipped with aftermarket Knight’s rail covers.

The lower receiver is marked as an AAC MPW with the three-prong BLACKOUT flash suppressor logo. The selector positions are marked on both sides of the lower receiver for safe, semi and full auto. Due to ATF restrictions, my test rifle was configured for semi-auto only. The MPW comes with Magpul’s excellent Magpul CTR stock and MOE+ pistol grip. Perhaps the best choice that AAC made was to equip the new rifle with a Geissele SSA trigger group. The unit has a match-grade pull while being robust enough for hard duty and military use.

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AAC barrels are made from 4150 CMV steel and feature a 1:7-inch twist that has been determined to be optimal for the 300 BLK cartridge. The barrel features M4 feed ramps and is black Nitride coated on both the exterior and the chamber/bore. The coating provides exceptional corrosion resistance and extends the life of the barrel. The full-auto bolt carrier group is hard chromed and consists of a shot-peened Carpenter 158 steel bolt, custom tuned extractor spring and a special O-ring.

Since the 300 BLK is specifically designed for suppressed use, the MPW comes standard with an AAC 51-tooth BLACKOUT Flash Suppressor/Adaptor. Back-up sights are largely a personal preference and AAC has selected not to equip the MPW with this option. After receiving my test rifle, I contacted Troy Industries and requested a set of their excellent Battle Sights with an HK-style front sight. I also mounted an Aimpoint T-1 Micro red dot optic with a 2-MOA reticle using a LaRue Tactical mount.

To maximize the 300 AAC BLACKOUT’s capability, AAC designed the 7.62-SDN-6 suppressor. The SDN-6 is 7.66 inches in length and features an Inconel baffle stack and front end cap to maximize durability. The construction allows the 7.62-SDN to be used on multiple platforms to include 7.62 NATO, 6.8 SPC, 5.56 NATO, and of course the 300 AAC BLACKOUT. It is also rated for full-auto in these calibers. According to factory specifications, the SDN-6 offers a 39 dB in sound reduction when using 300 BLK subsonic loads.

Range time with a suppressed rifle always attracts attention and the MPW was no exception. AAC had done their homework with regard to the 762-SDN-6 suppressor! The sound reduction impressed everyone who shot the SBR. Using the 200-gr. subsonic loads reduced the signature to what sounded like a loud staple gun. Even if the shot is heard, it does not sound like a gunshot. The combination gives the rifle a true covert capability that cannot be matched with a 5.56mm or 6.8 SPC platform. While the faster loads produce the typical supersonic crack, the suppressor still reduces the signature of the shot.

Probably no other standardized cartridge has a wider variety of loads than 300 BLK. I tested the MPW with loads that ranged from Gorilla’s 85-gr. Silverback load to SilencerCo’s 220 -gr. Sierra Match King offering. The MPW was 100% reliable with all of the loads in unsuppressed operations. This reflects the research that AAC undertook to properly “gas” the gun using an effective port diameter. It was interesting to note the difference between the 85-gr. Silverback that averaged 2,334 fps and the SilencerCo 220-gr. SMK that averaged 987 fps. The Silverback had a noticeable crack but had very little felt recoil while the SilencercCo had a reduced report with a recoil impulse of a mild push. I was disappointed to learn that the Silencerco load is no longer available.

Running the MPW with the SDN-6 suppressor installed increases back pressure and bolt velocity. I have found the suppressed MPW to be 100% reliable with subsonic loads and the medium weight supersonic loads such as a 155-gr. match load. However, when using lighter and faster bullets, it is possible to induce a bolt-override failure. This normally occurs with the last four or five rounds in the magazine and is caused by the magazine not lifting the next round fast enough to feed. If this occurs, the user should first ensure that the magazine is in proper working order and the magazine spring is at full strength. For those who want to use the faster loads on a consistent basis, the problem can be addressed by changing the recoil buffer.

On the range, I shot the MPW with four loads from a bench at 50 yards using the Aimpoint T-1 and 3X-C magnifier. As noted in the accompanying chart, velocities ranged from 2,300 fps to as low as 968 fps. The SilencerCo 220 sub SMK produced the smallest group at 0.60 inches for five rounds. That was closely followed by the 208 A-Max load from Gorillas with a 0.80-inch group. While the 85-gr. Gorilla Silverback load did not group as well as the heavier bullets, the accuracy is still acceptable for most applications.

Seven years after Kevin shared his vision with me, the 300 BLK is definitely here to stay. While not publicized, there are reports that specific units have used the cartridge in multiple operating theaters with great success. It is common knowledge that the United States special operations community has been evaluating the cartridge for some time with the goal of standardizing a weapon’s platform and cartridge. When this takes place, the 300 BLK will finally get the full respect it deserves. While Kevin Brittingham is no longer with Remington/AAC, his legacy will always be the 300 BLK.

Studio images courtesy of Camera1.

For more information, visit https://www.advanced-armament.com.

To purchase an AAC MPW on GunsAmerica.com, click this link: https://www.gunsamerica.com/Search.aspx?T=AAC%20MPW.

To purchase an AAC suppressor on GunsAmerica.com, click this link: https://www.gunsamerica.com/Search.aspx?T=AAC%20suppressor.