Tested XM177 moderator.

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Tested XM177 moderator.

Post by silencertalk » Sat Mar 04, 2006 3:41 pm

I always wanted to sound test a Colt NFA moderator, to know if it really reduces sound.

It is a very well made unit. Looks 100% satisfying.

Here are my sound results:

Colt 11.5 inch barrel, Winchester M193 ammo. 38 degrees, 43% humidity.

At the right ear, the XM177 moderator was 4.7 dB quieter than a fake XM177 moderator but a 20 inch M16 with A2 flash hider was 1.8dB quieter than the moderated 11.5 inch.

One meter left of the muzzle, the moderator was just 2.2 dB quieter than a fake XM177 but was 0.3 dB quieter than a 20 inch M16 with an A2 flash hider.

So what does this mean? It means that a moderated 11.5 inch will sound about the same to the shooter as a normal 18.5 inch. Yet the ATF regulates them as silencers.

I feel that if there is to be any silencer regulation at all, anything louder than a Ruger 10/22 should not be restricted -- as it will still sound like a gunshot. Just not the 'ear bleeding 168 dB' kind of gunshot.
Last edited by silencertalk on Sat Mar 04, 2006 5:37 pm, edited 1 time in total.

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Good Points

Post by Quietly-Effectively » Sat Mar 04, 2006 4:32 pm

Why don't people in Federal Gov't (ATF) think like you ? Where has liberty and the pursuit of happiness gone ?

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Re: Good Points

Post by Blaster7Romeo » Sat Mar 04, 2006 5:57 pm

Quietly-Effectively wrote:Why don't people in Federal Gov't (ATF) think like you ? Where has liberty and the pursuit of happiness gone ?
Becase they are not the ones that have the ringing ears like we do.

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Post by hcook » Sun Mar 05, 2006 4:06 pm

[devil's advocate]

Yes, but it does produce a reduction in SPL regardless of which gun you put it on.

[/devil's advocate]

The story as I understand it is that Uncle Sam was looking for a way to mask the presence of MAC-V SOG. Putting the moderator was supposed to change the sound of the report of the much louder commando length barrel to resemble the report of the regular M16, thus masking the identity of the soldiers.

Rob's testing seems to bear out that notion.

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Post by silencertalk » Sun Mar 05, 2006 5:50 pm

On a P22 with .22lr Green Tag ammo, it did 10 dB reduction dry and 15 wet.

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Post by Dynamite Dave » Mon Mar 06, 2006 3:21 am

I had always heard that the moderator was only intended to increase back pressure. This ensured more reliable functioning.

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Post by starduks » Wed Apr 04, 2007 6:53 pm

Dynamite Dave wrote:I had always heard that the moderator was only intended to increase back pressure. This ensured more reliable functioning.
i was told it was to change the report to make the XM177's sound like m16's.

saposidly the nva knew what an xm177 sounded like and that they were always carried by sog dudes. :roll:

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Re: MacV Weapons

Post by xandrespop » Wed Mar 11, 2015 1:53 pm

starduks wrote:
Dynamite Dave wrote:I had always heard that the moderator was only intended to increase back pressure. This ensured more reliable functioning.
i was told it was to change the report to make the XM177's sound like m16's.

saposidly the nva knew what an xm177 sounded like and that they were always carried by sog dudes. :roll:
This device was intended to be a BOOSTER! Not a Suppressor/ silencer .By Trapping the Gas, it cooled it /slowed it and as a by product silenced it a very, very tiny amount.... If the NVA knew anything to differentiate the sound of a CAR and a standard A1 it would have been rate of fire. The shorter gas system/barrel increased the cyclic rate a bit. That said a have spoken to several former MAC V fellas and they all relate using AKs when behind lines in Cambodia. NVA did not think twice when they heard the Clack clack of an AKM,...

As a side not The Large Bulgarian Muzzles devices Called a" Flame extinguisher" and used on the SU series {krink} is a Booster for the 8-9" barrel akm. HAs there ben any test of these 5.56 mm versions? Novesk copied it and that would be a good comparison to start from........

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Re: Tested XM177 moderator.

Post by silencertalk » Wed Mar 11, 2015 6:16 pm

I think they are quieter at the ear and louder out front.

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Re: Tested XM177 moderator.

Post by dtom29 » Thu Mar 12, 2015 9:40 am

Nobody is interested in publishing any tests of the 4 piece Bulgarian booster...We don't need another "moderator" fiasco. LEAVE IT ALONE>>>

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Re: Tested XM177 moderator.

Post by Mattitude » Tue May 26, 2015 2:10 pm

Silencertalk, do you have any detailed pics of the inside of the moderator? Also I would love to see some pics of the carbine that you used for the tests.
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Re: Tested XM177 moderator.

Post by L1A1Rocker » Tue May 26, 2015 4:13 pm

Mattitude wrote:Silencertalk, do you have any detailed pics of the inside of the moderator? Also I would love to see some pics of the carbine that you used for the tests.
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