Quest for the Quietest: MAC Tests 5.56 Suppressors

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From the Military Arms Channel:

I take out a collection of 5.56mm suppressors, a Bruel & Kjaer impulse sound meter and a bunch of IWI 5.56mm ammo to find out how well each of them performs following the Mil-Std 1474D protocols.

Suppressors used (and where you will find them in the timeline):
AAC M4 2000 – 4:34
AAC Mini 4 – 5:32
Silencerco Saker – 6:16
Silencerco Specwar – 7:07
Silencerco Specwar K – 7:51
Surefire SOCOM – 8:33
Griffin Armament M4SDII – 9:15
Griffin Armament M4SD – 10:02
Griffin Armament M4 SDK – 10:46
Griffin Armament Recce 5 – 11:30
Griffin Armament SPR – 12:15

Information on decibels and what it all means: http://www.acousticsbydesign.com/acou…

As the link above explains, 3db is technically a substantial increase in sound however what we hear as humans (perceived sound) it’s not quite noticeable (+5db and most people can hear an increase in sound). When talking about damage caused to your hearing, 3db can be meaningful even if the noise doesn’t sound louder to you as the shooter.

{ 7 comments… add one }
  • VirtualWatts June 21, 2016, 7:38 pm

    Thanks for testing.
    The B&K is 1971 analog technology before digital eliminated the Range dial, and throughout the demo you keep adjusting the range dial, which as I understand it is attenuating the 10 db range of the meter, a known limitation of the 2209. The dial requires you to know in advance and set the range of db for the test, or expirement and retest, but not adjust the range during the test as you do throughout the video. Probably shouldn’t keep adjusting the measuring equipment while performing tests.

    • Jon M August 1, 2017, 10:28 am

      To those complaining about “changing the dial during testing”, I don’t think you understand how the meter works. It’s perfectly acceptable to change the dial during testing. This simply aligns the needle near the center for user readability by pre-selecting the 10’s place of the readout. It does not affect accuracy of the reading. It only affects where the needle rests for a specific db level.

      For example, at the 150db setting, a 145db noise would read as -5db. But on the 140db setting, the same noise would read as +5db.

  • Mike Grant June 5, 2016, 5:56 pm

    Looked at your sound data for the 5.56 suppressors. The ammo you used, that was not a sub-sonic round. Thus the sound you record is both the rifle report, and the sound of the bullet breaking the sound barrier. This coupled with the berm or hill adjacent to your shooting site which will echo the sound, leads me to believe you have considerable contribution from the high velocity (“crack”) of the bullet. Something the suppressor can’t deal with. I found the sound from my Glock 17 9mm had the same issue. Suppressed; but not quiet. I reloaded to produce a subsonic round and the gun’s action is now louder than the pistol’s report.
    Michael Grant MD, PhD

    • whispershot June 6, 2016, 8:44 pm

      Doc. 556 rounds are typically not subsonic. There are subsonic rounds out there, but they are comparable to a 22LR, and the ones I’ve seen won’t even cycle the action of a typical AR. If you want an AR with great suppression capability you should consider the 300 blackout. A 300 blackout with the right ammo can be stupid quiet. The 556, on the other hand, is not going to be quiet using standard factory ammo. All that said, I still see value in suppressing a 556 rifle. A suppressed 556 is still much quieter than an unsuppressed rifle. I agree with your comments about the sonic crack in the video. The quietest suppressed firearms are 22LR, 9mm, 45 ACP, and 300 blackout (all coupled with subsonic ammo of course).

  • JACK SMITH October 30, 2015, 12:34 pm

    So, I am about to buy a couple of suppressors for my A/R 15 and my 1911. Should I wait????? I have been wanting them for a year now and have saved the $$. Does anyone think the Bill will pass and become Law by this Summer or should I just go ahead and “bite the Bullet” and start enjoying them now?

  • JMorgan October 30, 2015, 9:04 am

    Can you provide this info in table format so we don’t have to watch a 12+ minute video? Thanks for considering.

    • DRobertson December 27, 2015, 10:50 am

      Skip to 13:06

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