I know these are now considered "sound suppressors" but does anyone know how well they actually worked as far as db reduction? I've heard some fired, and they are loud!. I know they aren't hearing safe. Was considering an Innovative Ind. moderator, but hate to waste $200 if it literally does nothing. Thanks for your opinions.

Just happened by and saw this post.In 1979-1981, when I was in a USAF SP reserve unit, we had GAU-5/A/As and GAU-5/Ps.  A few of the GAUs had the moderator, and some didn't.  IIRC, The moderator brought the noise level down to rifle report, but the ones without the moderator (birdcage only) sounded like a 105 howitzer!  The moderators fouled badly, very quickly, and lost all effectiveness.  We had to soak them in a chemical concoction to clean them out.

I know that Suppressor Manufacturers aim for under 120 DB

Just from the size of it alone, it couldn't be very effective. I own a Gemtech  M4-02 which is kinda small, and even that isn't hearing safe on a 10" barrel, but is on 16 & 20".

It brought it down to between 155 and 160 so probably 5-7 at best.  But remember, decibels is not a linear function so 5 is big at that point (although you're still going deaf).  Those are just numbers I picked up on the internet.

There was a chapter in one of Gary Linderer's LRRP books, in which a moderator was removed and a standard flash hider put in it's place, just before a patrol to save on weapons length. The CAR15 was not test fired before the patrol, no contact was made while on the patrol, then later after returning to base the lurp function tested the weapon at the firing line. It was a single shot, the moderator was put back in place and everything was fine. I have often wondered if the moderators weren't simply for back pressure to cycle the weapons with the short gas systems. A lot of progress has been made in the last 40 to 50 years on short barreled AR's.





If I were going to do an SBR it would be an XM177E1 replica with no moderator. A little gas port and buffer weight work. Short and sassy.

Our 11.5" barreled GAU-5/A/As with the moderator removed, we opened up the gas port to around .10" in order to make them cycle.  I think it was .108" actually.  It was hard on gas rings, but they worked.

The only way a suppressor is going to be at or under 120 decibels is if you are shooting subsonic rounds. (as long as we're talking .223/5.56)  I don't know of ANY suppressor on a supersonic round, in 223/5.56 that is going to be hearing safe. That might be subject to argument, but I suppose what someone considers "hearing safe".   I'll go out on a limb here, and assume that we're interested in AR mounted suppressors, and their effects...........not on a bolt gun.  The sonic crack from a .223/5.56 isn't hearing safe, which effectively makes a suppressed AR not hearing safe, as you're gong to have to use supersonic round to function an AR.
  I'll add that I have a Surefire Socom RC 5.56 suppressor, and I can say that a suppressed 5.56 IS NOT quiet, not by any stretch of the meaning.   I can only imagine what a moderator DIDN"T do to reduce noise.  Now, having said all that, if I was wanting a real deal moderator, I wouldn't let the fact that it isn't going to do diddly squat slow me down.