Sound Pre and Post Air Tube Bottle Brush Depinger

I installed a bottle brush air tube depinger and cushioned the regulator spacer in my ongoing quest to quiet my Vulcan 22’s ping noises.
It was always a question in my mind whether the gun has an air tube “ping” or not. The best way to find out was to compare guns with and without,
but I only have one Vulcan 22. The majority of the objectionable twuung sound was already tamed with a foam earplug on the hammer spring.
The question was whether some of the sound was also from the air tube.

The bottle brush also includes an open foam segment. If anything was going to break up an acoustic wave, this would have done it.

Since I couldn’t compare two guns, I recorded the sound of mine pre and post modification using an AT200 microphone.
This is a good quality USB mic, not the lousy mic of a phone. The mic was on a mic stand and fitted with a pop filter.
I set about 1 foot to the right and 6 inches forward of the receiver block. The mic was kept as the same, manual, gain
for all recordings. Unfortunately, the exact distance between the gun and mic may shift one or two inches
due to my hold. None the less, you can hear the twuung in the recording.

I recommend listening with headphones to hear the sounds. On laptop speakers you may not hear it at all.
With good headphones the sounds are pretty close to live. The report is a bit louder than I notice while
shooting, but the twuung sound relative intensity and duration are pretty much what I hear live.
For an idea of how quiet the twuung noise actually is, compare against the loudness of the cocking action.

http://bunnyandbear.net/talon/2%20shots%20pre%202%20shots%20post%20tube%20depinger.wav

Two shots pre air tube depinger & spacer quietizing.
Two shots after the mods.

BTW That faint sound in the background during the first two shots is a treadmill one floor below.
The mic picks up quite faint noises.

I don’t think the mods made much of a difference.

My conclusion is that the Vulcan 22 does NOT have much noise due to a sound wave
bouncing in the air tube.

I may not have made my Vulcan any quieter with all the work today, but at least I now know
and can quit pondering whether the air cylinder and spacer were contributing noise.

The gun does get quieter with break in and silencing the hammer spring with a damper gets you 90% of the way there.

Just get DonnyFL’s device and John Hagan’s adapter and you are probably done.