5.56mm sound tests, July 2008.

**rsilvers** · 07-04-08, 00:19

Mic one meter to the left of the muzzle, A-weighted.

M4 14.5" with XM193, 169.0 dB

M4-2000, 134.4 dB, 4.1 dB FRP, 34.6 NSR, 16.9 oz, $895

AAC SPR/M4-K, 138.3 dB, 0 FRP, 30.7 NSR, 16.9 oz, $1050
(not our SPR/M4 but a special short version).

Surefire FA556K, 137.6 dB, 5.7 dB FRP, 31.4 NSR, 16.0 oz, $1265

Surefire OTB, 138.4 dB, 5.0 dB FRP, 30.6 NSR, 17.3 oz, $1265

M4-1000, 139.3 dB, 2.5 dB FRP, 29.7 NSR, 16.7 oz, $595

H&K 416 10" with M855, 166.0 dB

M4-2000, 130.7 dB, +4.5 FRP, -35.3dB NSR, 16.9 oz, $895

FA556K, 138.3 dB, +4.7 FRP, -27.7 NSR, 16.0 oz, $1265

Ranger2, 139.9 dB, 0.0 dB FRP, -26.1 NSR, $475

SRT Typhoon/Atlas, 144.0 dB, +1.2 dB FRP, -22.0 NSR, 24.3 oz, $745

**geezerbutler** · 07-04-08, 01:20

Nice post.

I'm sure this thread will generate a good bit of feedback.

Thanks

**JSandi** · 07-04-08, 01:32

Looks about an average of 35db reduction using a silencer.

I know that db's reductions are not linear, but I've read somewhere that just a 10 db increase in sound level corresponds approximately to a perceived doubling of loudness, is this true?

**Spooky130** · 07-04-08, 09:59

You get to have too much fun!

Question - could you show a picture of the SPR/M4-k next to the standard SPR/M4? I would have also liked to have seen the numbers for the standard SPR/M4.

Spooky

**rsilvers** · 07-04-08, 13:07

We have tested the normal SPR/M4 a lot. It is over 36 dB on an M4. There is about a 3/4 difference in length.

**Broadway** · 07-05-08, 21:13

Excellent post. You have helped me make up my mind on which to go with.

**No Bananas** · 07-06-08, 08:16

I'm surprised that the 14.5" was louder than the 10" unsurppressed. I'm also surprised that the Ranger2 fell about 4 decibles below advertised performance. Website also states 95% reduction, this test showed about 85%. The Typhoon also fell about 4 decibles short of advertised reduction.