[CodeToad]

I just did sound tests and here are some of the results.

No Silencer
4” barrel pistol: ~116db. Best: Federal 22 Subsonic (115.6db).

16.5” barrel rifle: ~113db. Best: 105db, Aguila 60gr subsonic (105.6db).

With Silencer
4” barrel pistol: ~99db. Best: Federal 22 target (98.4db), Aguila 60 subsonic (99db).

16.5” barrel rifle: ~98db. Best: 105db, Aguila 60gr subsonic (93.4db)

Basically, all weapons and ammo seem to center on 116db unsuppressed, and 96db suppressed. The suppressor provided 20db reduction. Some suppressor do up to 30db, but most 22cal suppressors only do 20db.

These numbers are also similar to what I measured using various rifle combinations of 5.56mm, 300 Blackout, 6.8, and 300 winmag. The 300 winmag was 144db and suppressed at 116db using a 30db can.

Rifles do tend to be quieter than pistols, but only by 3db. 22LR is quieter than 9mm, but still audible at many hundreds of yards. A suppressed 22LR is quiet at about 200 yards.

Quiet is relative, but I use the metric that if a sentry can hear it, then it is not quiet enough. A suppressed 22 using a 20db suppressor is quiet only past 200 yards.

Also, the First Round Pop (FRP) of the silencer is important. It raises the noise by 10db compared to the second shot. The silencer I was using did not experience FRP except on high velocity rounds like the CCI Stinger. Subsonic rounds did not experience FRP at all.

[LouAvul]

Your data is wrong. I've seen it. A movie called "The Killers" with Lee Marvin. He had a silencer on a Colt revolver (Detective Special, 38 cal). No noise out the cylinder/barrel gap. The sound was just a "puff." Plus, no recoil.

Are you saying I can't believe Hollywood? I'm crushed!

[marktwain]

What were you using for instrumentation?

Having reliable instrumentation and siting is an enormous problem in measuring sound levels of firearm reports.

It seems even instrumentation costing tens of thousands of dollars is problematic, because of differences in location of the instrument and orientation of the firearm.

3 db is reported to be a subjective noise reduction by half.

As to utility of suppressors, there are many situations where they have significant utility. In your example of a sentry, what is the background noise?

Is he located in the open, or in a forest?

Is there any wind?

A close friend told me of many combat uses of improvised/self-made suppressors. He said they had wonderful utility, simply in conserving hearing during use of M-16 rifles inside of buildings.