Author Topic: Fuel filter silencer  (Read 1186 times)

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Offline Baggawind

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Re: Fuel filter silencer
« Reply #10 on: January 20, 2021, 09:58:59 AM »
Well now i,m a bit peeved off. After buying one i thought i,d buy another couple , mainly because i gave the first one to a mate to experiment with . So i wanted one for myself and one for another pal. They arrived yesterday and , they have the wrong threads. As we all know , the standard thread for silencers is 1/2 x 20 unf.  Well these buggers are 1/2 x 28 tpi. Not what i ordered.  Looking once again at the adverts on Aliexpress and Amazon it seems they are no longer being made in 1/2 x 20. As i pointed in my first post , they were called fuel filters to get around some law or other. Well i reckon the authorities have cottoned on to that . I,ve run a 1/2 inch unf tap through but the result was not really satifactory . So i,m going to fill the threads with plastic metal and try again. It might work , who knows.

Offline Baggawind

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Re: Fuel filter silencer
« Reply #11 on: January 20, 2021, 02:40:48 PM »
On closer inspection of the website i found i could purchase separate 1/2-20 inserts. So, here,s hoping.

Offline 21grains

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Re: Fuel filter silencer
« Reply #12 on: January 22, 2021, 03:51:30 AM »
1/2 x28 is for Powder Burnners in USofA. That's why Bagg's. I'm going to buy one or two, just for the end cap's 1/2 x 20 & Tube 10" too long. 6" tube length is what I need weather I cut it and rethread it, job I can't do ! Sooooo what to do.....Franky

Offline Baggawind

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Re: Fuel filter silencer
« Reply #13 on: January 23, 2021, 10:13:43 AM »
I would suggest getting a six inch "filter" with a 5/8 x 24 female thread and then buy a separate 5/8 x 24 adaptor that has a 1/2 x 20 thread through the centre. Note , they make a fatter version with a 35mm o/d. And, if you buy one with the cones inside they MUST be drilled on a lathe as the small dimples on each cone are not all concentric . Either that or if you have to use say, a pillar drill and vice setup you will have to drill the holes to give plenty of clearance for the pellet to pass through. One old boy on Youtube drilled his using a vice grip and drill and did the drilling using the dimples. He landed up shooting his chrono as the pellets were clipping the cones on the way through.

Offline Gambo

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Re: Fuel filter silencer
« Reply #14 on: January 23, 2021, 02:11:17 PM »
I reckon you are right that the authorities have wised-up to the fact that they are bypassing the law by calling them fuel filters.

these buggers are 1/2 x 28 tpi. Not what i ordered.

Surely you have some 'come back' if you ordered 1/2 x 20 UNF and that was not the size supplied!!

Personally I would request a refund or they supply the correct threaded adaptor inserts FOC.

Offline Baggawind

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Re: Fuel filter silencer
« Reply #15 on: January 31, 2021, 10:47:49 AM »
After a lot of experimentation , i,ve come to the conclusion that these , slimmer filters offer very little by way of silencing.  I have however ordered a fatter type just to satisfy my curiosity.

Offline Gambo

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Re: Fuel filter silencer
« Reply #16 on: January 31, 2021, 12:10:48 PM »
It stands to reason, and experimentation, the bigger the volume the better the sound reduction.

Smaller silencers (think RWS Compact or even the Parker Hale) whilst very convenient, unobtrusive and neat, cannot match the sound absorption of bigger units.

Do you remember the Webley BBMF silencers of the late 90's early 00's? Made of aluminium, they came in two sizes, a 4" and 8". They were fitted with machined aluminium baffles, into which felt wads were added at a later date. The larger was very efficient sound wise, but geez they were a monster.........very big and very heavy. We experimented with the internal baffling of those in an attempt to reduce the weight but keep the effective silencing. But it was a futile exercise, as we could never get the weight down to an acceptable level as the main body was just too heavy.

I also tried to get the lighter weight aluminium bodied Parker Hale and RWS Compact to be more effective sound reduction wise. Again the work didn't reap any significant benefits, and we concluded the internal volume was just too small to retain the amount of expanding air exiting the muzzle.

But then manufacturers started to produce silencers in the 'Goldilocks' zone.......not too big, and not too small. These had thin walled aluminium (sometimes Carbon Fibre) bodies, with plastic internals. RWS was first (IIRC) and it was blinding, but that was soon eclipsed by the Weihrauch silencer.

AA and Swift silencers do a pretty close job, but none that I have yet tried can match the Weihrauch, which is why I have fitted them to all of my PCP's that can take them, whether via the 1/2" UNF thread or an adaptor.

Since doing all that experimenting years ago, which sound reduction was gauged by ear, electronic sound meters are now available on ebay etc for around the £15 mark. Having one of those back then would have made the testing much more subjective! Ahh Well.....I'm not doing it all again! ::) ;D

Offline Baggawind

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Re: Fuel filter silencer
« Reply #17 on: February 01, 2021, 09:16:55 AM »
You,re right about the silencers of old Gambo. I also had a Parker Hale , designed for firearms , and it didn,t come close to a Weihrauch. I have in my shed a Theoben silencer and it weighs a bloody ton , no use on a pnuematic . I,ve made several down the years , even copied the Weihrauch dimensions but even they don,t come close. I think the main difference , given the same dimensions , is the felt. I have tried 5mm felt , snooker table baize and insulation material used in clothing and none matched the HW one.

Offline Gambo

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Re: Fuel filter silencer
« Reply #18 on: February 02, 2021, 10:12:09 PM »
Spot on there Mel.

Whilst experimenting can be both challenging and fun, nothing matches the Weihrauch.

I too have a few Theoben silencers fitted to Rapid Mk2's. I removed the internal plastic baffle and turned it's O/D down to give clearance enough for it to be wrapped in felt wadding. There was no discernible difference, so I then had the muzzle of one screw cut by SFS so a Weihrauch silencer could be fitted.



Staying on subject but at a slight tangent......have you ever noticed that a certain brand of silencer can have varing results depending on the rifle it's fitted to?

For example, the Weihrauch is epic on the vast majority of PCP's, but the difference it makes doesn't seem so great when fitted to AA rifles.

Don't get me wrong.......it's still better than the AA silencer, but the improvement isn't as good as expected, or as dramatic as when fitted to an FX or summat, even when both rifles are producing identical velocity with the same pellet. I've concluded it must be a valving/harmonics thing. ???

Offline Baggawind

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Re: Fuel filter silencer
« Reply #19 on: February 03, 2021, 10:12:17 AM »
You,re probably right about the harmonics thing.  Another thing might be something to do with wether the rifle is regualted or not . Lower pressure being released perhaps. I don,t know.  The one that puzzles me is my Zbroia bullpup. That thing has a very slim shroud and a small labrinth baffle at the front and yet is extremely quiet . Whereas my Mapid has a large carbon fibre shroud . At the muzzle end of the barrel i fitted an air stripper then baffles in front of that. I have placed clothing insulation around the barrel , behind the stripper and vented the shroud at the breech end.  Despite all this it,s still not that quiet. I once read an article in the rifleman magazine . It was about the science behind silencers. At the end one company , after lots of experimenting , came up with a completely empty tube , the dimensions of which were critical. And it worked better than anything  else they had tried.  The downside was , they were asking around £400 for it. An empty tube !!!