BPM CQC 300 BLK pistol and AAC SR-7 silencer.

First, let’s address some terminology.

The silencer was invented around 1902 and patened in March 1909 by an American inventor Hiram Percy Maxim, son of Hiram Stevens Maxim who invented the Maxim gun. Maxim called the invention the Maxim Silencer. As a side, note the muffler for internal combustion engines was also developed around the same time of the silencer by Maxim using similar techniques.  So, initially they were called silencers by the man that invented the thing. I am well aware that the term suppressor is maybe more correct and more widely used but in the interest of correctness, I will be referring to the device as H.P Maxim intended.

Silencers have become very popular to own over the past few years and are not all that hard to get. There is some paperwork to the ATF, a $200 tax stamp, and a bit of a wait. I know that sucks but I reckon it is better than full on infringement.

On with the review, I reached out to AAC a few months ago to get some advice on a silencer to add to the Barnes Precision Machine CQB pistol in 300 Blackout I am reviewing.  After an informative conversation with Nick, I was well educated on silencers and had the paperwork submitted to the ATF to transfer a test sample of their new silencer, the SR-7, to use with my two AR-15s in 300 Blackout.

AAC offers the 762SD for rifles up to and including .30 caliber and it is a fine silencer to be sure but the newer SR-7 has some improvements such as a 90 tooth ratchet mount over the 51 tooth ratchet mount for the 762-SD. The 90 tooth ratchet taper™ system minimizes point of impact shift so there is no change in accuracy by adding or removing the silencer.

I tested this claim using the BMP CQB Patrolman’s Rifle in 300 BLK , Hornady 208gr subsonice and 125gr supersonic ammo, and Defender 150gr full metal jacket supersonic ammunition. From a rest, using iron sights, at 100 yards I was consistently able to print two inch and under groups with the rifle and ammo. Group size did not change at all when the silencer was added or removed. Note, the rifle and ammo will print better groups with optics as I did shoot a few that were tighter but two inches at 100 yards with iron sights is about as good as I can shoot.

For the test, I incorporated the BPM CQB pistol, in 300 BLK.

After the silencer was nice and broke in, I measured the noise reduction at 32 decibels using 300 BLK supersonic ammunition.  Now my sound meter is not the most expensive but I got pretty consistent results so I have to believe the measurement is very close.


I tested the BMP CQB pistol in 300 Blackout with a few accessories, AAC SR-7 silencer, a Magpul angled foregrip (which I recommend for AR style pistols), and a Magpul single point sling. The optic was included as it is being reviewed as well. The CQB pistol ships standard with magpul flip up sights. The rear is adjustable for windage and the front is adjustable for elevation.


I did not need the forward assist during the review but it is still there and a comfort to many. The magazine release is also serrated in a circular pattern which is important in keeping traction when dropping a magazine with wet or gloved hands. The trigger broke clean at 6 pounds.


The safety and bolt release are serrated for traction and worked exactly as they should.


The Nickle Boron coated bolt carrier group.


Notice the M4 type feed ramps, enhancing feeding reliability. This CQB pistol does not have an adjustable gas system


The Advanced Armament Corp SR-7 Silencer. An excellent silencer that did well getting the subsonic rounds to 130 db and held up under a lot of use and abuse.


The new 90 tooth flash hider that is compatible with the SR-7


Silencers are cool, period. Also, they can make shooting much more enjoyable and less intimidating to the neophyte. I personally like AR style pistols. When I talked about the 10 1/2 inch barrel being ideal for the 300 Blackout I was taking into account several factors, not just velocity. Overall length plays a part, to sacrifice a little velocity to gain maneuverability in a CQB type firearm is acceptable. While forming my opinion of the system, I was keeping in mind performance, maneuverability, reliability, accuracy, and the manual of arms. When shooting the 16″ barrel as compared to the 14″ barrel with supersonic and subsonic ammunition there was actually velocity loss. Now that only averaged about 20 fps and that had no impact on ballistic gel penetration or accuracy as that is minimal loss. I did learn you get the absolutely best velocity, on average, from a 14″ barrel and when going to shorter lengths velocity loss was no where near as bad as the 5.56 x 45 (.223 Remington), This lends the 300 Blackout to preform well in short barreled rifles. I have close to 1000 rounds through the CQB pistol test sample with no malfunctions or problems. It did cycle with subsonic as well as supersonic ammunition.

I also talked about the AR type pistol, being considered a pistol, and in many states would fall under a concealed carry permit. While true (again check your local laws to be sure) this platform is not really conducive for concealed carry on your person. It, however would be a fine candidate to conceal in a vehicle.

We tested the 300 Blackout in 7 1/2″, 9″, 10 1/2″, 14″, and 16″ barrels with supersonic ammunition.

barrel length  velocity  ballistic gel penetration, 100gr ballistic tip

7 1/2″              2110 fps         18″

9″                     2188 fps        18 1/2 ”

10 1/2″            2226 fps        20″

14″                   2274 fps        22″

16″                  2257 fps         22″



Advanced Armament Corp


Barnes Precision Machine

Stillwood Ammunition

Defender Ammunition

Specifications on the silencer

7.62 NATO & 300 BLK
19.6 oz
Sound Reduction:
25dB – 39dB*
90T Ratchet Taper Mount
Inconel® 718, 316L SS

MSRP $1200

Specifications of the BPM CQB 300 BLK pistol

MSPR: $1308.30

Sig SB15 Stabilizing Brace and Magpul MOE grip.

Magpul MBUS sights with front sight adjustment tool.
7.5″ SS  300 Blackout
BPM A2 Style Flash Hider / Breaching Tip.
Exceptional Quality -Commercial grade /semi auto AR15 Fire Control group.
BPM Bolt Carrier Group w/Nickel Boron coating.
  • Mil Spec 7075 forged upper/lower.
  • Upper receiver, lower receiver and handguard hard anodized to Mil Spec Type III specifications.
  • All BPM Inc. lowers feature adjustable tension screw and detent retention set screw for rear takedown pin detent .
  • Pistol length gas system
  • 7.5″ 416 stainless steel barrel blanks. CNC machined in house with 300 Blackout chambers.
  • BPM Inc. PSFFRS Ultra-lite Extreme 7″ Handguard complete with quick detach sling swivel inserts.
  • Every BPM rifle ships with Patriot AR Case with custom high density foam inserts, Users Manual with Warranty and one Magpul PMAG

For more information on the silencer please email salesinfo@advanced-armament.com




By Hunter Elliott

I spent much of my youth involved with firearms and felt the call early on to the United States Marine Corps, following in my father's and his brother's footsteps. Just after high school I enlisted and felt most at home on the rifle range, where I qualified expert with several firearms and spent some time as a rifle coach to my fellow Marines. After being honorably discharged I continued teaching firearm safety, rifle and pistol marksmanship, and began teaching metallic cartridge reloading. In the late 1990s I became a life member to the National Rifle Association and worked with the Friends of the NRA. Around that time my father and I became involved with IDPA and competed together up until he passed away. I began reviewing firearms for publications in the mid 2000s and have been fortunate to make many friends in the industry. Continuing to improve my firearms skills and knowledge is a never ending journey in which we should all be committed. I am also credited as weapons master on a few independent films.

11 thoughts on “BPM CQC 300 BLK pistol and AAC SR-7 silencer.”
  1. Looks like you need to update your video, showing and telling people that that “pistol” is legal to shoot from the shoulder. ATF just ruled against it because so many sucker wannabes were using the pistol brace that was designed for disabled people as a stock just because they’re too cheap to pay the tax and too impatient to wait their turn for a form 1.

    1. Instead of saying people are “too cheap” or “impatient” as if you know what other people are thinking, consider what Hunter said in that this weapon since is not governed by NFA. And this is why you may want to consider it. So you don’t need any government permission to posses or transport this across state lines. And if you want to sell it to someone they don’t have to get government permission either. As far as legality of shouldering the brace, this is an unenforceable ruling. As long as you don’t record yourself doing so there is no way they can know you did. This would be like a law that says you can purchase alcohol if your under 21 but you just can’t drink it. How the hell are they going to know?

  2. Very cool set up running the 300 BMP Blackout pistol with the AAC SR-7 can. I appreciate you going through the pistol and silencer so well. Thorough and unbiased, what I was looking for.

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