Learn something new about suppressors...

[Motorhead]

As I think about this further my mind wanders on designs that address this to some degree.



If we use term of lets say NUCLEOLUS ( being Center of this sound waves frontal wave ) and we look at this sound wave as stated 2 posts above being peeled away by the baffles leaving the center or nucleolus undisturbed, it exits first with nearly all the amplitude it started with following the pellet. All the peeled away sound energy now muffled exits as the pressure within the LDC collapses.



If we look at advanced designs such as many Powder gun silencers as well EDGUN notably .... The baffle Partitions are on SHARP OPPOSING ANGLES in and out of each chamber space. What this is doing by design is peeling away the pressure wave NON UNIFORMLY which IMO destabilizes the nucleolus or the sound wave enough so it has an otherwise as or more quite Muffling effect even tho hole size generally is larger. Even if holes threw system are kept small the effect of destabilizing the nucleolus of the sound wave it is a more effective devise design. Hard as hell to fabricate and why we don't see commercial after market manufacturers using it.



JMO and deeper thoughts ...



Scott S

 

[JimNM]

Scott, all I have is my experience. I don't have a sound meter. I am not a fluid dynamics engineer. I stand by me assertion that a .22 moderator vs. a .25 moderator will be undescribable without a sound meter. Same gun, same ammo, different caliber of the same moderator. I want to see the numbers. Can you provide empirical evidence?

 

[Odoyle]

When I block the LDC exit hole with a smaller sized exit hole restrictor closer to the actual caliber size it sounds quieter according to MY ears.

 

[Odoyle]

Speaking if caliber specific moderators/shrouds...

When I put my 22 caliber Allen Z (AZ) Theoben Rapid shroud (22 caliber specific) on my 177 Rapid it's definitely night and day louder than when on my 22.

When I put my 20 caliber AZ shroud (20 caliber specific) on my 177 Its still louder than when on the 20 but the sound difference is not as much as when going from 22 to 177.

 

[Motorhead]

Scott, all I have is my experience. I don't have a sound meter. I am not a fluid dynamics engineer. I stand by me assertion that a .22 moderator vs. a .25 moderator will be undescribable without a sound meter. Same gun, same ammo, different caliber of the same moderator. I want to see the numbers. Can you provide empirical evidence?

No i can not ... We will agree on disagreeing leaving it at that.

 

[JimNM]

+1

Shoot'em good

 

[mtnGhost]

I can possibly see that as an error margin thing for poor shroud designs (or moderators made from weak materials), but that is an awful rumor that is out there (that all airguns should go one caliber larger). I had a conversation with Neil Clague a little while back, and he just couldn't fathom why anyone would do that. You lose so much effectiveness doing so!

DonnyFL is standing by their product, telling me it will be perfectly centered to the barrel. Donny has a good reputation so I'm trusting they know what they're talking about.

You missed the point that I made. He's sold god only knows how many moderators, it's easier on the customer service front to say go up a size than explain the geometric problems around concentricity in relation to poorly threaded barrels or poorly threaded / machined shroud systems. 

I can possibly see that as an error margin thing for poor shroud designs (or moderators made from weak materials), but that is an awful rumor that is out there (that all airguns should go one caliber larger). I had a conversation with Neil Clague a little while back, and he just couldn't fathom why anyone would do that. You lose so much effectiveness doing so!

So true! When the threads are cut concentric to the bore all is good! Going up a size is for poor quality control. I wish our airguns were all up to the standards of custom firearms—our barrel threads are cut for no run-out, and suppressors and barrels are threaded as perfectly concentric to bore as possible.

This

It all comes down to ALIGNMENT ..... ANY place in the stacking of shrouds, air strippers, threaded LDC adapters and even the LDC them self can be places where a degree or fraction of a degree of TILTING or CONCENTRICITY changes relative to the barrel bore deviate from parallel & true.

Thus why the Caliber higher sizing is suggested for most guns and applications. THIS IS A CRUTCH FIX to a cumulative poor tolerance & machining of the parts and pieces before entering ANY LDC devise. Tho if the LDC threading and the face edge it tightens against is not square and true it still will likely clip pellets if at caliber spec sizing.



Scott S

..and this in broader detail!

...and yet there is no detectable penalty for going up in size. Don't worry about the small stuff, IMHO.

This is incorrect. The moderator with the smaller diameter is noticeably quieter than an identical moderator with a larger bore diameter. I'm not an acoustical scientist, rather result-driven - and this is the result that I am sure of in every instance that I have compared!! 

The bottom line: if your goal is having the quietest shots, you should choose the moderator with the smallest bore diameter for your caliber. If you're clipping in a moderator built for the caliber that you are shooting, then you have others problems to deal with (unless you're ok with sacrificing louder report as a crutch). 

At the end of the day, it's your airgun and money - so do whatever you feel is right for you.

 

[steve-l]

I know most of you folks do not have access to a machine shop and all the associated tools they would contain, but I do. I make my own moderators. Bore to baffle clearance does make a difference, Not as much as you would think, but it IS noticeable. More important is the accuracy lost if the moderator alignment to the bore is not in-line regardless if clipping occurs or not. I have made a few rods made from precision shafting that I place in the barrel bore through the moderator to validate concentricity. They give me confidence of the moderator to bore alignment after installation, which I do after every disassembly of the barrel shroud. It only takes a minute to do. I use .020" barrel to moderator bore clearance and have found running any tighter clearance has no noticeable benefit.