June 10, 2015 | 0 Comments

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

By Hunter Elliott

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.”