The Science of silencers

[Phil Russell]

Looking at the price of airgun silencers these days yesterday. Crikey they tend to be expensive varying from the cheap end at around £60 up to over £100. Now I wonder why? Is it the manufacturing cost? ... I can't see materials being that expensive but can appreciate that there will be several steps involved in making one. Does 'design' come at a price? This leads to my 'Science of silencers' title. Are silencers 'designed' according to known parameters and so could be patented? I don't recall seeing a patent number but this could easily be because the profits to be made are too low to warrant costs of a patent or patents. Are there any publications that detail the 'science of silencer design'? Or is it all a case of 'suck it and see'....... if it works then it goes into production?
Any thoughts?
Cheers, Phil

[MartynB]

Never really thought about it. I have two silencers made for me in the very late 1980's early 1990s. Only ones I ever bought were Galway units with barrel / tube adapter, Innova had one hell of a crack without

[u.k.neil]

Hi Phill, The material costs are minimal and with CNC machinery, so is the time taken to manufacture the components. However the machinery to make them are initially extremely expensive and the cost has to be amortised as quickly as possible. The basic design of moderators is engineeringly wise very simple and basically variations on a theme. With this I mean engineered moderators, not those filled with hair curlers and felt.

When I was a R.F.D. I could make a moderator from scratch on single purpose machinery in under an hour and that included making "K" baffles to fit inside the tube and threading both of the tube ends and making the threaded end caps.


Neil.

[Phil Russell]

Hi Phill, The material costs are minimal and with CNC machinery, so is the time taken to manufacture the components. However the machinery to make them are initially extremely expensive and the cost has to be amortised as quickly as possible. The basic design of moderators is engineeringly wise very simple and basically variations on a theme. With this I mean engineered moderators, not those filled with hair curlers and felt.

When I was a R.F.D. I could make a moderator from scratch on single purpose machinery in under an hour and that included making "K" baffles to fit inside the tube and threading both of the tube ends and making the threaded end caps.


Neil.

Hi Neil ... good to hear from you.
Interesting view but a thought came to me (ouch!) what would you cost your time at for an hour's expert lathe work and the knowledge of what to do? I won't guess but I tend to think that for a man of your skill it could be significant.
Cheers, Phil

[32:1]

The last mainstream silencer I bought was an AM nelix, £120 and although good it smarted a wee bit and I had a look around and Ive been using a guy called Hal from Halifax, he makes bespoke silencers and shrouds and I’ve got to say their excellent, I don’t know how he makes them for the money, my last two were for an hft500 and an mpr barrel on a Kral which didn’t need the cylinder cap relief, made to my spec and in carbon, his silencers and shrouds are probably the quietest I’ve used apart from the huge Nelix, Ive made some diy shrouds and been happy but for a another £20/30 Hal’s stuff is brilliant and just not worth the hassle of DIY

[Maciek]

I have one of this , and it's working

https://www.youtube.com/watch?v=xf2D...gunPestControl

[u.k.neil]

Hi Neil ... good to hear from you.
Interesting view but a thought came to me (ouch!) what would you cost your time at for an hour's expert lathe work and the knowledge of what to do? I won't guess but I tend to think that for a man of your skill it could be significant.
Cheers, Phil

Hi again Phill, it has been about ten years since I packed in making bits and pieces, but back then I was quite happy making £30 an hour in my garage. But don't forget I was retired and this was a bit of a hobby that I enjoyed, but going back to a commercial business with all the equipment already bought and amortised I would estimate C.N.C. machining time for all the parts at less that 2 minutes plus another couple of minutes for assembly and packaging.


Neil

[Phil Russell]

Hi again Phill, it has been about ten years since I packed in making bits and pieces, but back then I was quite happy making £30 an hour in my garage. But don't forget I was retired and this was a bit of a hobby that I enjoyed, but going back to a commercial business with all the equipment already bought and amortised I would estimate C.N.C. machining time for all the parts at less that 2 minutes plus another couple of minutes for assembly and packaging.


Neil

Jeepers Neil ... very few things in life I have managed in two minutes ... or even four for the complete job
Seriously though, this could be an indication that there could be money in silencers.

But to my main question: is there science behind their design or is it mostly try it and see? As an example, some (many ?) silencers use baffles. How is baffle spacing determined? Exit hole: how is the diameter calculated? Could it vary with pellet velocity? OK ... I realise calibre has to have an influence, but what?
Has anyone published on this?
Cheers, Phil

Cheers, Phil

[Geezer]

https://www.firearmsnews.com/editori...c-dater/524909

The recently late, great, Phil Dater, who I had the pleasure of meeting some years back. Suppressor guru. Great books.

[greenwayjames]

It should be noted that as the UK law stands at present making and selling of air rifle silencers requires the person to be a Registered Firearms Dealer (RFD) and as such the silencers must either be collected face to face from the RFD or sent to another RFD for collection by the customer. An RFD is contravening the VCR act if he puts a silencer in the post direct to a customer. Silly, but there it is. The law is the law and applies to all.

[angrybear]

It should be noted that as the UK law stands at present making and selling of air rifle silencers requires the person to be a Registered Firearms Dealer (RFD) and as such the silencers must either be collected face to face from the RFD or sent to another RFD for collection by the customer. An RFD is contravening the VCR act if he puts a silencer in the post direct to a customer. Silly, but there it is. The law is the law and applies to all.

Well that could be debatable, I used to believe the above to be the case, but in investigating the current plans to remove mods from FAC's I discovered sub 12 mods are not classed as component parts (chap 12.77)
Which would seem to remove the RFD requirement on manufacture of firearms &/or their component parts (chap 2.3),
However I'm unsure of the requirements when it comes to selling airgun mods by way of business, which may still need RFD status.

If they are a RFD yes the VCR restricts sale by post & even airgun mods must be recorded in their register.

[greenwayjames]

Well that could be debatable, I used to believe the above to be the case, but in investigating the current plans to remove mods from FAC's I discovered sub 12 mods are not classed as component parts (chap 12.77)
Which would seem to remove the RFD requirement on manufacture of firearms &/or their component parts (chap 2.3),
However I'm unsure of the requirements when it comes to selling airgun mods by way of business, which may still need RFD status.

If they are a RFD yes the VCR restricts sale by post & even airgun mods must be recorded in their register.

That's one of the many silly things. It has always been the case that individuals can send silencers in the post but if you sell them by way of business, even at cost, you are still required to be an RFD and then restricted by the terms of the VCR act.

[Bellycrawler]

Many years since I experimented with different baffle designs. Useing shop bought ones to see what was inside & a lot of reading up on them . As for the internals there is a wide variety from the awfull waste of money to simple effective science to verry clever sales man designs, slightest change makes a big difference & the most annoying is different silencers react differently on different rifles. No simple answer but I guess for the best effective silencers your paying for knowledge gained over many years. With others they have a high latest fashion price.

[Phil Russell]

Some very interesting comments so far but my impression is: that nobody sits down with pen and paper and designs a silencer using scientific guidance/formulae or whatever. Unless I am corrected by an expert in the field I will go away with the thought that a 'design' is tried almost by 'rule of thumb' and the results are noted. Variations are then made e.g to internals or body diameter and/or length to see what effect they have and to see if they make an improvement. Can the effect of these changes be predicted? For the most part I do not think so although the experience of the maker could have an influence. But the scientific reason why a change could be beneficial is not known ... it is all down to experience. This process will be/could be repeated until the maker, maybe an individual or a company decides that what they have ended up with is the best they can do within the parameters they are working with .... price, overall size (maybe) and design.
Apologies if my view offends anyone ... I would welcome being corrected and being told how silencer parameters are used to predict an end result rather than a 'let's try this and see' scenario.
Cheers, Phil

[Bellycrawler]

From my understanding there is a lot of science, trial & error, fashion. In the UK we are blessed with a wide variety that are on the shelf & readily available. One thing to consider, upgrades ie better than the last provides new sales when the old product works perfectly well. Over the years I've heard / read so many comments such as so quiet I could hear the hammer (pcp) a sound meter is needed, the brain can & does switch off sound. When I done tests in a very amateur way I tested sound levels at the point of target. No good if we hear silence when the "target" hears boom ! One thing I found, some pellets whistle in flight. Deflect air flow, disturb air flow, rapid initial air expansion (release of high presure) slow release exiting the silencer (low to equal air pressure).