Placement and need for venting holes in moderators?

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fe7565

fe7565

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Oct 13, 2015
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VA, United States
I noticed that 0db and DonnyFL (and possibly others) have venting holes placed in the moderators. 0db seems to have it towards the end where it mates to the barrel, while Donny's has small holes towards the front. I assume that they are there to allow for the slow beed off the air pressure. 

But why is the hole(s) placed on the moderator near the immediate exit of the barrel, and why is the other one placed near the pellet exit side of the moderator? Even if the internal chambers are arranged in a different way, one would think that it makes a fundamental difference if the air being slowly exhausted/bled in the very first vs. the very last chamber? 

Also,is that just a mesh screen on the 0db or it has some intricate air passages below that? 

0db-compactblack-1.1607699067.png
Sumo1_250x2502x.1607699118.gif

 
If the LDC engineering is good enough then vent holes are not necessarily needed like the AZ design and HW and several others like hair curlers or screen or springs wrapped with scotch brite material separated by washers. If the design internals are really junk and useless and only for decoration and taking up space you won't see anyway hacksaw them in 1/3s first 2 chambers of equal lengths and last chamber longest and separate with washers and or last chamber use a compressible spring wrapped with scotch brite type material or just toss them internals out string them up to plink at and redo the guts yourself hair curler or mesh screen scotch brite time last active baffle chamber weak spring wrapped with scotch brite or just make your own from scratch for example from the $10 Aliexpress housing that's like the Emperor and improve mod the guts.
 
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The other Aliexpress $18-$20 that looks like the Huggett swirl would be a good start too.
Click to expand...

I tried that, and a Homeland Security Agent phoned me at home and warned me that it is illegal to import such Chinese items and U.S. Customs had seized my order.

BEWARE...unless you want Uncle Biden sniffing up your shorts on his "Persons of Interest" government security list!!!



Uncle Hoot
 
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Thank you for the information. I see the Huggett connection with the 0db. So the first chamber is for rapid expansion? And the other two chambers should be larger in size? While only one chamber has vent holes? Is it because in the first chamber that high pressure air would make an audible sound escaping? 

Kind ol' Uncle Hoot is correct. I made a mistake of ordering one from AliExpress thinking that it's really a fuel filter and I can easily adapt it for an airgun LDC Then I posted here on AGN naively telling about my "great find" vs the $200 moderators. I was quickly enlightened by others what it is used for and my thread was quickly shut down and I was banned for a few hours until I appealed and explained. By the way my order still has not showed up and has been in the same status for weeks. I do not think I will ever receive it, nor do I want it now, finding out about the situation around it. I really do not want Uncle Biden up in my ass anymore than he already will be... Also, let's not talk about that AliExpress item here anymore, do not want to get banned. 


 
Upvote 0
The other Aliexpress $18-$20 that looks like the Huggett swirl would be a good start too.
Click to expand...

I tried that, and a Homeland Security Agent phoned me at home and warned me that it is illegal to import such Chinese items and U.S. Customs had seized my order.

BEWARE...unless you want Uncle Biden sniffing up your shorts on his "Persons of Interest" government security list!!!



Uncle Hoot
Click to expand...

I thought it was only young girls hair.
 
Upvote 0
The other Aliexpress $18-$20 that looks like the Huggett swirl would be a good start too.
Click to expand...

I tried that, and a Homeland Security Agent phoned me at home and warned me that it is illegal to import such Chinese items and U.S. Customs had seized my order.

BEWARE...unless you want Uncle Biden sniffing up your shorts on his "Persons of Interest" government security list!!!



Uncle Hoot
Click to expand...

I thought it was only young girls hair.
Click to expand...

😂
 
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Thank you for the information. I see the Huggett connection with the 0db. So the first chamber is for rapid expansion? And the other two chambers should be larger in size? While only one chamber has vent holes? Is it because in the first chamber that high pressure air would make an audible sound escaping?
Click to expand...

I have made my own moderators for AGs, but I am not an expert. From what I have read and experienced in my own "designs". The first chamber (after the muzzle of the barrel) should be the largest for better expansion and the latter "chambers" can be modified for tone/frequency of the sound that actually exits.

While more baffled chambers can reduce the overall DB level, tuning for frequency can also be as, if not more valuable.


Some of the best moderators I have "heard" were simple 2 chamber devices. (my own creations...)

BTW, I have also found, at least for me and my ears, that ScotchBrite (or equivalent) works better in most cases than acoustic felt. But I have not done much experimenting in a long while and my "designs" may just lend themselves to be better using the ScotchBrite type material.

p.s.

What I make are "slip-on" and use hair curlers (Dollar Tree), 1 inch PVC tubing, metal washers or grommets (Harbor Freight), ScotchBrite equivalent (Dollar Tree) and, of course, duct tape. This worked very well for the Freedoms I own, but as the shroud diameter for the Fortitude is smaller, I have not found a good way to make one for that. As quiet as the Fortitude is, it is still MUCH louder than the Freedoms with my DIY moderator(s) at the same velocity/FPE.
 
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The fortitude needs scotch brite not too tightly wrapped around weak wire springs separated by washers. Make your own springs is best to experiment on making your own perfect diameter springs to multi layer wrapped felt thickness ratio.

Small diameter weak spring make a fat sushi roll scotch brite takes up majority of the diameter. Self centers too. Blows out against shroud wall keeps exit path clear.

Active baffles at work. Lube the scotch brite with some oil.
 
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I have been making moderators for more than 40 yrs. I have tried lots of ideas over those years. So much of what we read is BS. In my experience, vent holes do not not make moderators quieter. In point of fact, they become louder. Stuffing the inside of moderators with anything only changes the tone of the report, if that. The practice does NOT make the report quieter. Multiple expansion chambers and large chamber volumes does work in making the moderator quieter. My experience is the same as Backstop's experience, the first chamber should be the largest. Wrapping the outside of the moderator in a sound absorbing wrap can make the report quieter. This is especially true with PBs.
 
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