# How do silencers work and can I build them? **URL:** \ **Category:** Factual Questions\ **Created:** [April 13, 2006, 9:38pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581 "2006-04-13T21:38:50Z")\ **Posts on this page:** 18\ **Page:** 2
**Author:** ![Martini\_Enfield](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/martini_enfield/32/11123_2.png) [@Martini\_Enfield](https://boards.straightdope.com/u/Martini_Enfield)\ **Post date:** [April 14, 2006, 1:52am UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/21 "2006-04-14T01:52:39Z")
Silencers were (and still are, I believe), totally 100% no strings attached legal in NZ, and when I was growing up there I did a fair bit of shooting with silenced rifles and handguns. One of the rifles was a Stirling .22, in which the barrel was also the silencer (much like on the MP-5SD 9mm SMG), and when you pulled the trigger, all you could hear was a muffled “Click”, and a rabbit would suddenly drop dead 25m away. Very cool. Silenced pistols (great for indoor ranges!) made a muffled “Shuonk” noise when fired (just like something out of a James Bond film, actually!), but their range is greatly reduced (a silenced .22 might get 15m of accurate shooting- 10m to be on the safe side). Silenced 9mms made a similar noise, but the silencer really affected their accuracy at anything beyond 15-20m or so. As for how they actually work: Silencers have a series of vents or “Chambers” in the silencing tube that allow the gas and soundwaves to “expand” behind the bullet, noticeably reducing the sound of the gunshot. As others have noted however, it’s all a moot point if you’re using Supersonic ammunition (can you say Sonic Boom?) It’s worth mentioning that the only revolver that can be effectively silenced is the [Nagant M1895](http://en.wikipedia.org/wiki/Nagant_M1895). The NKVD (forerunner of the KGB) used these during WWII for, well, the sorts of things you’d expect the NKVD/KGB to be using silenced handguns for. Oh, and while I’m here: _“In the West, you silence gun… in Soviet Union, gun silences you!”_ I’ll get my coat… 😃 ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [April 14, 2006, 2:36am UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/22 "2006-04-14T02:36:01Z")
> [@Stranger On A Train](#): > > I have fired a properly licensed and stamped silenced weapon (H&K MP5…not the SD version, but an professional-grade aftermarket silencer.) I have to admit that I was quite suprised at how much it attentuated sound; with the use of 149 grain subsonic hollowpoints, you could clearly hear the operation of the action over the report, and the muzzle blast was reduced from a crack to kind of a dull thump. > > Stranger The great thing about the factory SD version, is that it actually dumps the velocity of the rounds. So normal rounds will leave the weapon subsonic. One of many reasons that weapon is so damn quiet. In fact, you should never use subsonic rounds in an MP5SD. The rounds will dump so much velocity they’ll be close to ineffective… even by 9mm standards. ---
**Author:** ![Throatwarbler\_Mangrove](https://avatars.discourse-cdn.com/v4/letter/t/8c91f0/32.png) [@Throatwarbler\_Mangrove](https://boards.straightdope.com/u/Throatwarbler_Mangrove)\ **Post date:** [April 14, 2006, 3:00am UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/23 "2006-04-14T03:00:59Z")
Supressors on longer range weapons such as sniper rifles and machine guns are quite useful, especially at night, where muzzle flash is often the only way to determine the origin of a shooter without night vision equipment. [Here](http://www.sfu.ca/casr/id-macpher-4.htm) are some pictures of silenced GPMG/M240 and 5.56mm rifle. All our (Canadian) [current](http://www.pgwdti.com/id2.htm) sniper weapons, including the [famed .50 cal Mcmillan Tac-50](http://www.sfu.ca/casr/101-tac50.htm) come standard with supressors. 1. Generally for rifles, muzzle velocity is increased, as the barrel is effectively lengthened. 2. The biggest problem for the bigger suppressed sniper rifles is that the rising heat from the suppresor will cause distortions to the sight picture. ---
**Author:** ![The\_Long\_Road](https://avatars.discourse-cdn.com/v4/letter/t/b5a626/32.png) [@The\_Long\_Road](https://boards.straightdope.com/u/The_Long_Road)\ **Post date:** [April 14, 2006, 3:28am UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/24 "2006-04-14T03:28:30Z")
> [@LiveOnAPlane](#): > > You are quite correct in this. It is not going to fool people into not realizing they are being shot at. > snip Having been shot at and missed by a very small amount, you will know you are being fired on, silencer or not. The sound the bullet makes as it passes by is very distinct, even if it is subsonic. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [April 14, 2006, 5:42am UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/25 "2006-04-14T05:42:52Z")
> [@The Long Road](#): > > Having been shot at and missed by a very small amount, you will know you are being fired on, silencer or not. The sound the bullet makes as it passes by is very distinct, even if it is subsonic. But not the location from where the bullet originated, which is the point. That being said, the use of silencers by snipers is vastly overstated in film and television. Stranger ---
**Author:** ![nd\_n8](https://avatars.discourse-cdn.com/v4/letter/n/439d5e/32.png) [@nd\_n8](https://boards.straightdope.com/u/nd_n8)\ **Post date:** [April 14, 2006, 1:07pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/26 "2006-04-14T13:07:48Z")
IIRC, In Indiana silencers and fully automatic weapons are leagal to own with the right documentation, but I’m not sure about the legality of making one. I do know that, if one wanted to try out a silencer or full-auto or any other type of gun, Don’s in Indianapolis rents guns. I’ve thought about renting one and spending some time with a couple of 8 x 10s of my ex, but they probably wouldn’t allow that. ---
**Author:** ![Zjestika](https://avatars.discourse-cdn.com/v4/letter/z/8edcca/32.png) [@Zjestika](https://boards.straightdope.com/u/Zjestika)\ **Post date:** [April 14, 2006, 8:40pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/27 "2006-04-14T20:40:00Z")
> [@Shagnasty](#): > > My father was a firearms dealer and we had a fully automatic silenced Uzi as well as a Mach 10 when I was growing up. They made me quite popular with my friends and I shot them many times. I wonder how popular you were after shooting all your friends. 🙂 ZJ ---
**Author:** ![The\_Long\_Road](https://avatars.discourse-cdn.com/v4/letter/t/b5a626/32.png) [@The\_Long\_Road](https://boards.straightdope.com/u/The_Long_Road)\ **Post date:** [April 14, 2006, 9:12pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/28 "2006-04-14T21:12:37Z")
> [@Stranger On A Train](#): > > But not the location from where the bullet originated, which is the point. > > That being said, the use of silencers by snipers is vastly overstated in film and television. > > Stranger true, the point of a silencer is to conceal your location but the statement was that it kept people from knowing they were being shot at. I was simply stating that if the round comes anywhere near the person, they will know that someone is shooting at them. ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [April 14, 2006, 9:46pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/29 "2006-04-14T21:46:32Z")
> [@Surbey](#): > > First, how exactly does a silencer for a pistol/rifle work? I’m interested in how exactly it reduces the noise so much. Second, can I build them myself? By build them, I mean two things. Is it legal for me to manufacture one myself (I live in Indiana if that helps) and would a person using a nonspecialized set of tools be physically capable of building one? There is a book of Silencer patents, Try Brownells gun supply. Forget pop bottles, totally ineffective. Manufacture requires precision machining and custom fitting to a gun for best results. ---
**Author:** ![Whammo](https://avatars.discourse-cdn.com/v4/letter/w/8dc957/32.png) [@Whammo](https://boards.straightdope.com/u/Whammo)\ **Post date:** [April 14, 2006, 10:06pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/30 "2006-04-14T22:06:43Z")
> [@LiveOnAPlane](#): > > It’s kinda like the flash suppresor on the end of the barrel, also subject to much myth. The flash suppresor is not there to keep the folk being shot at to be unable to see the muzzle flash, it is to keep the shooter from being temporarily bling by his/her own muzzle flash. AHH!!! NOW I get it… thank you! I always wondered how they prevent someone from seeing the flash. Now I know. THEY DONT! ---
**Author:** ![Throatwarbler\_Mangrove](https://avatars.discourse-cdn.com/v4/letter/t/8c91f0/32.png) [@Throatwarbler\_Mangrove](https://boards.straightdope.com/u/Throatwarbler_Mangrove)\ **Post date:** [April 14, 2006, 10:15pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/31 "2006-04-14T22:15:10Z")
> [@Whammo](#): > > AHH!!! NOW I get it… thank you! I always wondered how they prevent someone from seeing the flash. Now I know. THEY DONT! …but a silencer/suppressor will. ---
**Author:** ![DougC](https://avatars.discourse-cdn.com/v4/letter/d/7feea3/32.png) [@DougC](https://boards.straightdope.com/u/DougC)\ **Post date:** [April 17, 2006, 1:16pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/32 "2006-04-17T13:16:47Z")
- - - Yes you can build your own silencer, _if_ you can get a tax stamp in your state. And you need to get the tax stamp first. Some states effectively ban ownership by not allowing you to complete the paperwork properly; I dunno what’s legal in Indiana. - Silencers are not difficult to make, a few hand tools and some welding or brazing method is enough. I saw people do it for fun when I was younger. In the US, the penalties for getting caught are pretty severe however. [http://www.norcom2000.com/users/dcimper/assorted/mischief/columbo.html](http://www.norcom2000.com/users/dcimper/assorted/mischief/columbo.html) - The Howstuffworks site is a lousy example of a silencer; the best types are the Maxim recurve-baffle but due to the peculiarities of US laws you can’t get any good examples in the US at all. One website that has good cutaway images is the site for Reflex Suppressors: [http://guns.connect.fi/rs/](http://guns.connect.fi/rs/) ~ ---
**Author:** ![mrrealtime](https://avatars.discourse-cdn.com/v4/letter/m/e8c25b/32.png) [@mrrealtime](https://boards.straightdope.com/u/mrrealtime)\ **Post date:** [April 17, 2006, 1:36pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/33 "2006-04-17T13:36:18Z")
> [@Zjestika](#): > > Quote: > Originally Posted by Shagnasty > My father was a firearms dealer and we had a fully automatic silenced Uzi as well as a Mach 10 when I was growing up. They made me quite popular with my friends and I shot them many times. > > I wonder how popular you were after shooting all your friends. ROTFL ---
**Author:** ![Scumpup](https://avatars.discourse-cdn.com/v4/letter/s/ce73a5/32.png) [@Scumpup](https://boards.straightdope.com/u/Scumpup)\ **Post date:** [April 17, 2006, 1:44pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/34 "2006-04-17T13:44:19Z")
A very good friend of mine designs and builds silencers. To answer the OP: 1. It reduces sound by reducing the velocity and the temperature of the firing gases. The “wet” suppressors contain a little liquid, usually lithium grease but can use water, to help in this process. Inside the suppressor tube are baffles. Overall, it isn’t too different from a car muffler in concept, though they do differ in construction. 2. Yes, you can build one yourself. According to my friend, nothing you could build with common hand tools would be worth the effort. At the very least, a lathe is required. 3. At the federal level owning a silencer is legal, though there is paperwork and tax stamps involved. Indiana state law may say no and your local laws may say no. You’d have to check into that yourself. Email me and I’ll give you some additional information that I don’t care to risk modwrath by posting here. p.s. The soda bottle will work, but poorly, for one or two shots from a **.22lr or smaller.** Again, out of fear of modwrath, I will not give details because doing it w/o BATF paperwork is illegal. ---
**Author:** ![Tristan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tristan/32/18058_2.png) [@Tristan](https://boards.straightdope.com/u/Tristan)\ **Post date:** [April 17, 2006, 4:02pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/35 "2006-04-17T16:02:08Z")
> [@Stranger On A Train](#): > > But not the location from where the bullet originated, which is the point. > > That being said, the use of silencers by snipers is vastly overstated in film and television. > > Stranger Intersting thing of note… From everything I’ve read, our snipers are trained in their use, but our snipers very rarely use them, as they severaly reduce accuracy at any sort of range. But former Soviet (and presumably modern Russian) forces almost always utilized suppressed rifles, as their engagement distances tend to be much closer than our snipers. Pictures from the Chechen conflict show Russian forces using Suppressed SVD’s, and Chechen using captured SVD’s also suppressed. Excellent topic! ---
**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://boards.straightdope.com/u/matt)\ **Post date:** [April 17, 2006, 5:06pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/36 "2006-04-17T17:06:34Z")
Some nice cutaway diagrams of expansion-chamber-and-baffle supressors: [Reflex Suppressors for M62 Finnish Assault Rifle](http://guns.connect.fi/rs/m62graaf.html) These supressors work by partially capturing and regulating the expansion of the propellant gases behind the bullet. The baffles are solid and “non-wiping”, i.e. the bullet passes through the baffle stack without touching them. In theory, such a suppressor shouldn’t affect accuracy and will also reduce recoil by capturing some of the forward momentum of the propellant gases. An older design uses"wiping" baffles of rubber or some other elastomer. The holes in the baffles are smaller than the bullet, so they “wipe” the bullet as it passes through them. This can affect accuracy, and the baffles are eroded by each shot. AFAIK, this type of supressor was only used on handguns. I’ve heard of suppressors where the expansion chamber was packed with wire wool or the like, the idea being that the high surface area of metal would cool the propellant gases and extract some of the energy from them. That design seems to have passed out of favour. The “wet” suppressors use a similar principle, in that the water or grease is vapourised by the propellant gases, cooling them in the process. The only “wet” suppressor design that I’ve seen had the expansion chamber internally cross-hatched with grooves to hold the water or grease. > [@Martini Enfield](#): > > Silenced pistols (great for indoor ranges!) made a muffled “Shuonk” noise when fired (just like something out of a James Bond film, actually!), but their range is greatly reduced (a silenced .22 might get 15m of accurate shooting- 10m to be on the safe side). Silenced 9mms made a similar noise, but the silencer really affected their accuracy at anything beyond 15-20m or so. Do you happen to know if the silencer used wiping baffles, or even a wire wool pack? A non-wiping silencer shouldn’t have harmed accuracy, or at least that is my understanding. > [@Tristan](#): > > From everything I’ve read, our snipers are trained in their use, but our snipers very rarely use them, as they severaly reduce accuracy at any sort of range. I think in the case of rifles, the reduction in accuracy comes from using low-power shells to make the bullets subsonic. With supersonic ammo, a suppressor doesn’t necessarily compromise accuracy, although the sights may need adjustment. The suppressor won’t silence the weapon in that case, but it will make it harder to locate the shooter by sound, hide the flash and protect the ears of the shooter. From the site linked above, bolding mine: “Suppressor **does not increase group diameter of shots in target or object.** Additional weight on barrel shifts the place of group center on M62 and other Kalashnikov family weapons typically at 100 m by 10…18 cm to the right and up, **but that displacement is easily corrected by adjusting sights.** More extensive off-aiming or sight adjustment may be needed, when using subsonic rounds. Trajectory of subsonic bullet is also very curved.” ---
**Author:** ![Tristan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tristan/32/18058_2.png) [@Tristan](https://boards.straightdope.com/u/Tristan)\ **Post date:** [April 17, 2006, 5:39pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/37 "2006-04-17T17:39:28Z")
> [@matt](#): > > I think in the case of rifles, the reduction in accuracy comes from using low-power shells to make the bullets subsonic. With supersonic ammo, a suppressor doesn’t necessarily compromise accuracy, although the sights may need adjustment. The suppressor won’t silence the weapon in that case, but it will make it harder to locate the shooter by sound, hide the flash and protect the ears of the shooter. > > From the site linked above, bolding mine: > “Suppressor **does not increase group diameter of shots in target or object.** Additional weight on barrel shifts the place of group center on M62 and other Kalashnikov family weapons typically at 100 m by 10…18 cm to the right and up, **but that displacement is easily corrected by adjusting sights.** More extensive off-aiming or sight adjustment may be needed, when using subsonic rounds. Trajectory of subsonic bullet is also very curved.” Indeed, it appears that a lot of research and information is now out there that I didn’t have in the past. This is a good thing. In fact, according to their claims, the Surefire silencer in the link about claims to improve the rounds velocity and to potentially improve accuracy, as the suppresor acts as a slight extension to the barrel. I must admit, I’m learning a lot, and am VERY curious to find out what one would have to do to purchase/manufacture a suppresor in PA… ---
**Author:** ![Scumpup](https://avatars.discourse-cdn.com/v4/letter/s/ce73a5/32.png) [@Scumpup](https://boards.straightdope.com/u/Scumpup)\ **Post date:** [April 17, 2006, 6:46pm UTC](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581/38 "2006-04-17T18:46:45Z")
> [@Tristan](#): > > Indeed, it appears that a lot of research and information is now out there that I didn’t have in the past. This is a good thing. > > In fact, according to their claims, the Surefire silencer in the link about claims to improve the rounds velocity and to potentially improve accuracy, as the suppresor acts as a slight extension to the barrel. > > I must admit, I’m learning a lot, and am VERY curious to find out what one would have to do to purchase/manufacture a suppresor in PA… Pennsylvania permits ownership of suppressors following BATFE legalities. Your municipality may have other ideas, however. [Previous page](https://boards.straightdope.com/t/how-do-silencers-work-and-can-i-build-them/352581.md?page=1)