How do silencers work and can I build them?

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?

Yes and yes, with a maybe. It’s probably huge heap of paperwork and various tax stamps and licenses. It probably also requires basic gun smithing tools.

Funny, I was just thinking about this the other day. Great minds think alike :slight_smile: . This site gives a solid explanation of the science behind silencers. I am not too certain about your second question so I will defer to someone with more knowledge of gunsmiths.

The license required to manufacture one is harder to get than the tax stamp to purchase/possess one. So, the logical thing to do is just buy one.

Keep in mind that they’re not nearly as effective as movies and TV imply, with the shot reduced to a little “choop!”

What about using a plastic soda bottle as a silencer (as I saw in an episode of CSI)? How well would that work?

About as well as expecting DNA tests to come back before the end of the day, I think.

As I understand it, it would work illegally.

Yes, but would it muffle the noise at all well? (Not that I’m planning to do so. I’m just curious. Of course, this thread might just get locked at any moment.)

Interesting. We can’t talk about how to do something illegal. But is it okay to talk about something illegal if you don’t say how to do it?

In defense of this thread, making a silencer out of a plastic 2 liter bottle is just as legal as making it out of anything else. Provided you get a Manufacturers License from the ATF.

Oh, and even the best silencers only atenuate around 30-35 decibels. Which is on par with the best sets of hearing protection and/or ear plugs. So if you want to know what a weapon sounds like with a silencer, pop in some ear plugs and shoot it. It will sound about the same.

Only if you’re in an anechoic chamber. In the real world, attenuating sound at its source will sound different than attenuating it at your ears. It also seems quite likely that attenuation by frequency profile of a silencer may well be radically different from that of hearing protection, even if the total measured attenuation is the same. Based on what you’ve said, though, the two should sound about the same loudness, even if they doesn’t sound the same.

I have never used a silenced firearm.

I did see a silenced Uzi on video. The sound was sort of a ‘chuf-chuf-chuf’ plus the sound of the bolt. A friend of mine was in the army, and he heard a silenced pistol. He said there was no sound but the sound of the slide. (This is second-hand information to me, so take that for what it’s worth.)

Also remember that a lot of the noise comed from supersonic bullets. I pulled targets at a rifle competition once, and it was just as noisy in the pit – 1,000 yards away from the shooters – as if I were standing right next to the shooter. There are subsonic rounds for use with silenced pistols. I don’t know if subsonic rounds are available for rifles.

It isn’t completely illegal to make or possess silencers but they are regulated under the same laws as machine guns and short-barreled shotguns. Assuming you live in a state where they aren’t completely outlawed, the federal regulations are still very combursome to do it legally. This applies as much to your coke bottle silencer or a .22 as it does for an Israelli made silencer for an Uzi. Not complying with the regulations can get you in a world of federal hurt.

Here is the basic process for “transferring” one to yourself which means buying:

" The transfer involves paying the transfer tax, which is $200
for all the NFA weapons, except AOW’s for which the tax is a
mere $5. Individuals also have to get one of several specified
local chief law enforcement officers to sign the form (see the
section on the law enforcement certification for more
information), submit their fingerprints in duplicate, and attach
photos of the transferee to the form. While the transfer tax is
levied by law on the transferor (seller), in practice the
transferee (buyer) is expected to pay the tax. Transfers to
individuals tend to take at least 4 months, although subsequent
transfers can be quicker. "

Getting a permit to make any one at all is even more cumbersome.

Complete details here:

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. The silencer was as long as the Uzi was however so it added a lot of barrel length.

The sound of the Uzi was basically as you described. You mainly just heard the action slamming shut as nine 9mm bullets cycled through it a second. It wasn’t exactly quiet but it didn’t sound that much like a regular firearm either. It sounded like a really quiet jackhammer. You could shoot one in a house without people hearing it too far outside. That is quite different from an unsilenced automatic weapon.

I wonder what kind it was. The MK23 is still pretty freaking loud, even with a silencer. That silencer works a little better wet though. But the water doesn’t stay in it for more than one or two shots.
.22s with integrated silenced barrels are pretty quiet. But they still sound as loud as those Snap Cap things you used to throw on the ground as a kid. Remember those things?
I never fired a silenced Uzi, but I assume it’s quite similar to the MP5SD. Similar in loudness anyway. One New Years I brought an MP5SD and a Glock 18 to the party. After 1 mag through the SD, I realized how stupid a silenced subgun is for New Years. So the next 1000 rounds were put through the Glock instead.
The MP5 is pretty damn quiet. But I’m still not convinced that all I’m hearing is the bolt cycling. It sounds louder than that to me. The “chuf chuf chuf” sound described is pretty good. But I suck at onamotopoeia. And spelling.
Silenced M16s and M4s are a joke. They’re still loud. As said before, they’re about as loud–actually louder–than shooting with just ear protection in.
But they can’t be heard from as far away, and they are so much better for firing inside of buildings. The weapon is unbearable indoors without a silencer. Especially hallways and small echoey rooms.

Aren’t M16 rounds supersonic? Doesn’t matter how big your muzzle suppression is, it’s not going to prevent a miniature sonic boom from being heard.

First of all, silencers work by reducing the velocity of escaping gases. They do this by a variety of methods–baffles, meshes, containment–but the result is the same; to reduce the gas speed and resultant muzzle blast. As others have pointed out, a bullet traveling at supersonic speed will have its own sonic wavefront; using a silencer to reduce the report can make it somewhat more tolerable to fire (and this is, or at least was, required in Germany for hunting) but it won’t completely silence the weapon. Law enforcement and military special tactics sometimes use silenced submachine guns or assualt carbines, not to escape detection but to reduce the ear-drum shattering noise to a tolerable level without wearing muffs. Here is SureFire’s page on suppressor silence.

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. It doesn’t sound anything like the “shshh” sound you hear on the televisor, of course, but then, foley artists don’t accurately replicate the sound of a real gunshot, either. There are specialty shops that produce small caliber (.22LR, .25ACP) locked-action pistols with integrated silencers that are supposed to be very quiet, and a number of Q-Branch-esque pistols using specially designed silenced ammunition, but I have no experience with those.

As for the famed 2-litre bottle silencer, it’s strictly a one-shot deal and (so I’m told, as I would never do such a thing) not terribly effective for any serious caliber (.38Spl and above) of firearm. It’s really not worth the potential trouble with the Revenuers to play with this.

On the topic of the legality of building one, you’ll have to check state regulations and see if it’s even allowed. Federal regulations for possesion merely require paying for the tax stamp and submitting the form, assuming that you’re a US citizen and not a felon. Manufacture regulations are more complex, though if you’re building one strictly for personal use there may be an exemption.


You are quite correct in this. It is not going to fool people into not realizing they are being shot at.

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.

The purpose of silenced rifles is not to keep the folk being shot at from not knowing they are being shot at. They will hear the supersonic whipcrack of the projectiles. What this does do, though, is by suppressing the…the, uh, “discharge boom” it helps hide the LOCATION of the shooter.

I guess I should also mention that while Federal law allows for the licensing of silencers and automatic weapons, some states do not. Gotta check this if you want to have such.