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″
Specifications on the silencer
7.62 NATO & 300 BLK
25dB – 39dB*
90T Ratchet Taper Mount
Inconel® 718, 316L SS
Specifications of the BPM CQB 300 BLK pistol
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.
For more information on the silencer please email firstname.lastname@example.org