What makes a PCP quieter…?

[RangerPete]

Here’s a question for the more informed members of this forum…

What makes an air rifle quieter…?

Barrel length, 500mm vs 600mm vs 700mm?
Shrouded barrell? Fully shrouded or no shroud?
Moderator/silencer size, length and or thickness? Empty or baffled?

Is one factor more important that others, or is it best to use a combination of some or all of the above?

Thanks for the knowledgeable info that I’m sure will follow
Pete.

 

[JimNM]

IMHO, the biggest factor will be valve control. No wasted energy pushing from wasted air. Get that valve closed asap and the noise level goes down.

 

[EdinGa]

Tuning for the best efficiency will enhance the effectiveness of a longer barrel, shroud or moderator. Wasted air equals noise.

 

[Stubbers]

I don't care how well tuned an airgun is, without a proper length barrel, shroud and moderator they will BARK. I wouldn't say tune is the biggest factor, wasted air never blew my ear drum but not shrouded and no moderator certainly has. Heck try removing the barrel all together on a finely tuned airgun, so barrel length has much greater effect than all the above if you get really technical, a 3-6" barrel won't care what tune you throw at it.

Tune would be last of the three imo.

-Matt

 

[EdinGa]

I don't care how well tuned an airgun is, without a proper length barrel, shroud and moderator they will BARK. I wouldn't say tune is the biggest factor, wasted air never blew my ear drum but not shrouded and no moderator certainly has. Heck try removing the barrel all together on a finely tuned airgun, so barrel length has much greater effect than all the above if you get really technical, a 3-6" barrel won't care what tune you throw at it.

Tune would be last of the three imo.

-Matt

I agree and that's why I said tuning will enhance the effectiveness.

 

[nervoustrig]

I think Matt and Ed have it pretty well covered. Just wanted to comment that the fundamental thing you want is to minimize the residual pressure at the end of the barrel (or the moderator...whatever it is that represents the last thing constraining the expanding gas before it reaches the outside world).

In practice, the things that help are the things already mentioned. A moderator and/or shroud, a long barrel, and short valve dwell. Of these, the one typically having the greatest influence is a moderator. Even a small-ish moderator will have a volume which is a significant percentage of the barrel volume, giving the gas a much larger space to expand into, and baffles help slow it down to spread it out over a longer period of time.

 

[Lewis]

It is heavily situational. Some guns only have one barrel length available or don't offer methods to control the valve. So The answer becomes somewhat hypothetical. If you are asking what methods during design would have the biggest effect then controlling valve timing may be the most important. If that is out of your control, then the volume and baffle design of the moderator would likely have the largest effect.

 

[socalboarder]

Thanks for the great breakdown

 

[JimD]

Nervoustrig covered it well but I will add that an empty shroud doesn't work close to as well as one with baffles. It is because it doesn't drop the pressure as much or spread out the release of air from the muzzle. My P35s with baffles and "the hair curler mod" are as quiet as they are with a printed moderator in the shroud. Either is as quiet as the Donny Tanto I own. Even my little Prod with a little bit of baffling is noisier than my P35s. My Avenger with an open shroud is pretty noisy.

I would also speculate that a properly tuned barrel of 450 mm is as quiet as a 700 mm barrel. The advantage of the long barrel is it is easier to get the valve closed well before the pellet exit so the pressure can drop. But that is controlled by the tune. The shorter barrel will not make as much power but it can be quiet. If you tune the 700 mm in a way that leaves the valve open closer to the pellet exit than with the 450mm it could be noisier.

 

[Rawroots]

The volume of air is my thought, the other day i layed a bath towel folded over my suppressor and was surprised how quiet it sounded.

 

[Mike-K]

Keep it in the closet. Sorry, having a pile of Donny FLs, shroud mods. and others, I couldn't resist

 

[mercado]

Parting from that the gun is at full power.. that being 100fpe + so a monster of a gun ..it will only be mouse fart quiet with a really big full shroud with deep cone baffles.. take as a example the taipan.. so far I don't know any other airguns with the taipan baffles .. design that are deep conical baffles.. there are many with baffles but not like the taipan..that even in high power is a pretty quiet gun , imagine if that shroud was 2" thick .. it will sound like if it wasn't even shooting..

 

[subscriber]

mercado,

What do those taipan baffles look like?

Something like these:

Taipan Veteran shroud baffles

Somehow ended up with an extra set of aluminum baffles and spacers for a standard. Also have (6) 3D printed baffles, but no spacers. Quiet it down a little more by adding more baffles. Aluminum set with spacers/ $50- tyd. 6 3D printed baffles $30/ tyd.

www.airgunnation.com

OR

Taipan Vet baffles

Good morning everyone, I just made a oups move. I took my baffles out of my Vet. to check how they work and try to use the idea behind the good system that they have to quiet down my son's Bullboss. But by doing so, I scrambled the puzzle before taking a pic. Now I don't know if the Long...

www.airgunnation.com

OR

Taipan Mutant

"Verve"Could one of your guys please share the picture(s) of the mutant's baffles? This guy posted pics of them in his review: http://www.network54.com/Forum/79537/thread/1432336761/Taipan+Review I was looking for a pic too to save me opening my shroud. I was dying to see what made it so much...

www.airgunnation.com

Thanks

 

[Motorhead]

Controlling Valve DWELL so the valve is open no longer than required in extracting the power required is Key !!
Pressure is the primary source of energy we use to launch a projectile .. Releasing more air than required at any operating pressure will just add to the muzzle report / noise.
FACT !!