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rsilvers
07-04-08, 00:19
Mic one meter to the left of the muzzle, A-weighted.

http://www.silencertalk.com/photos/july2008test/metering_mg_9586small.jpg


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

http://www.silencertalk.com/photos/july2008test/556K_mg_9623small.jpg

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

http://www.silencertalk.com/photos/july2008test/ranger2_mg_9617small.jpg

http://www.silencertalk.com/photos/july2008test/556k_mg_9613small.jpg

http://www.silencertalk.com/photos/july2008test/AAC-SUREFIRE_mg_9622small.jpg

http://www.silencertalk.com/photos/july2008test/M4-2000_mg_9624small.jpg

http://www.silencertalk.com/photos/july2008test/SPRM4K_mg_9619small.jpg

http://www.silencertalk.com/photos/july2008test/SRT_mg_9618small.jpg

http://www.silencertalk.com/photos/july2008test/SRT_mg_9645small.jpg

http://www.silencertalk.com/photos/july2008test/SurefireOTB_mg_9641small.jpg

http://www.silencertalk.com/photos/july2008test/m4-2000_mg_9636small.jpg

http://www.silencertalk.com/photos/july2008test/556K_mg_9642small.jpg

http://www.silencertalk.com/photos/july2008test/M4-1000_mg_9643small.jpg

http://www.silencertalk.com/photos/july2008test/SPRM4K_mg_9644small.jpg
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.
kevin/aac
07-06-08, 08:44
The Ranger was originally designed for 14.5" barrels. That silencer is also a little more ammo dependent. XM193 is worst case.
LonghunterCO
07-06-08, 09:12
I had seen posted by NickB that the M4-1000, althought having a low price point, was not an can low on preformance. This is a great post. Thanks.
Boss Hogg
07-06-08, 20:47
Great info.

Can you share point of impact shift and group size variance between the various models tested?
cyclone72
07-07-08, 15:01
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?


They are more logoryhtmic as in waves.A difference of 3 decibels is when a most ears can discern a change of reduction or increase in sound.An increase of ten can be signifcant comsidering the normal threshold for hearing safe with limited exposure is 140 decibels.
rsilvers
07-07-08, 15:12
It depends on the frequency, but somewhere between 6 dB and 10 dB change is considered twice as loud to a human.

We are confident that we have the best POI shift performance of any company.
BookHound
07-08-08, 10:55
We are confident that we have the best POI shift performance of any company.

I've done a lot of testing with my 762-SD and M4-2000, both '08 models. I'd have to agree with POI shift being so little it is mostly non-existent. Put a weight on a barrel and there is no 100% guaranty, but the odds are high that with the AAC product you’ll have little to no POI shift.

Mark
decodeddiesel
07-08-08, 11:16
Pretty interesting tests for sure thank you for posting! It is pretty amazing how much louder the XM193 is than M855, especially considering a 10" piston system vs a 14.5" DI system. I do have some questions and concerns however.

I am curious as to why you used XM193 for one gas system/bbl length and M855 for the other? Also why were different cans used? I understand anything the reflexes will not work on the 10", so ergo were you using cans that were designed for that barrel length specifically?

Also why did you use a DI gas system for one barrel length and a piston for the other?

I am confused as to the 3rd figure, the "NSR" figure. Why is it negative with the 10" piston and positive with the 14.5" DI? For that matter what does "NSR" standfor? I understand the first round pop (FRP) but I don't know what NSR stands for.

Finally is there a mil protocol you were following? ETA: MIL-STD-1474D

Thanks! I am glad to see posts like this, they really provide good empirical data which would heavily effect purchase of these items.