Barrel Sound Signature

[MANN]

My point is that you can make lots of measurements, but the marker setup has a lot to do with it and needs to be recorded as well. A friend's new viking sounded like a real gun for half a day. After about a case of paint I thought he had changed markers because I didn't hear it anymore. He had not done anything to it.

The sound reduction should be the same as long as the same marker is used with all barrels.

[Warwitch]

The best marker I haven't heard was a cocker with about a 16" stiffi on it. It also had some timing issues.

Without ports, if you can time a cocker so that the ball has no pressure behind it when it hits the ports or muzzle, you'll get nothing but ball. It means the ball has to be going well over the target muzzle velocity before it gets there. Accuracy probably suffers a too.
.

I would second that. Ive seen a Freeflow that was nearly silent. All you could hear was a light *click* of the p-block. That was actually what made me fall in love with them.

[drg]

Pipes have forward-angled ports intended to project sound.

[thejere]

crazy cool, I have to look at the whole test post, but it looks like you were fairly thorough.
any dry fire numbers in there?

I am imagining a a paintball moving down a barrel like the cone the cone of a speaker, so the sound is created by the dissipation of energy; the ball exiting and the extra gas (pressure) venting. Same size and mass paintball exiting at the same velocity should create the same dBs on its way out the barrel, right? So that would be like a base level of noise. The rest should be from the extra pressure that has to vent and where it vents from. Porting is not big enough to allow for unrestricted air flow, so a lower volume over time will exit through it then down the end of the barrel. The more high pressure gas exiting the barrel tip, the louder the barrel? Sounds plausible. Did happen to keep track of turning up/down the input pressure to the marker in relation to noise? My completely pulled out-o-the butt theory on how to make a quite barrel is as follows

longer over all length for gas to expand and pressure to drop
longer back (I believe in rule of 8")
Port after eight inches, right to the end, at least six inches of porting

Well, I've jumped to some big conclusions, anyone with a background in compressible flow on AO to help me out?

[ThePixelGuru]

used ~ 6 types of paint & reballs. we measured many of the paintballs (took a sample study).. All of this stuff is listed in the "test"

I meant Spencer's test, which is separate from yours... or is this all data from the same test?

[MANN]

I meant Spencer's test, which is separate from yours... or is this all data from the same test?

all mine. he just copied and pasted.

[Spencer]

all mine. he just copied and pasted.

Yes, sorry, I did not claim this as my own, I thought I stated that somewhere..

All I did was arranged the numbers in order from least to greatest. I had no input in the tests. Never met man..

[Spider-TW]

all mine. he just copied and pasted.

You mention the actual versus the advertised bore dimensions. I looked for it in there (pbn), but didn't see any comparisons. Did I miss it?

**edit** I forgot about post #7 while I was reading elsewhere. Maybe someday?

Also, while you have all that fresh data on ball sizes, would you be able to throw out some standard deviation numbers? I would be nice to know what the manufacturers are holding lately.

[Pneumagger]

ALong with the Decibel measurements, Could you post up:

barrel lengths
combined porting area
bore diameter
Porting pattern

Given identical paintballs and shot from the same platform - these will be the largest factors.

Longer barrel will be quieter.
More porting is generally quieter.
As aereal desity of the porting increases near the breech it will get louder.
Too much overbore will be louder.
A lower pitched tone carries distance better than a higher pitched tone.

[Spencer]

A lower pitched tone carries distance better than a higher pitched tone.

True, but a higher pitch sound is easier to locate and is perceived as louder than a lower pitched tone..

[Pneumagger]

True...

I much prefer the thump of a good wet .45acp suppressor to a higher pitched "quieter" 9mm suppressor even if the 9mm is by definition quieter by 3-4dB.

[Spencer]

Well I just ordered a 16" Deadlywind barrel, I'm sure its going to be super quiet..