Status: Urban Legend
The
Miami Herald reports the case of a man who threatened to shoot the mother of his child with a gun silenced by a potato. He never fired the gun, but did explain to her how the potato would silence the shot, insuring that no one would hear what happened. The police had this to say about the man's knowledge of acoustics:
The vegetable, while rich in carbs, does not make an effective silencer, police say. The myth dates back to mob murders of the 1920s and has persisted through movies and word of mouth.
"It was fine in Dick Tracy, but in real life, it's not true," said Miami-Dade Sgt. Bob Hoelscher, a longtime firearms technician who is not involved in the case. The sound of a gunshot can be suppressed somewhat if the gun is low-caliber and the cartridge is weak enough, Hoelscher said. But it usually makes a mess.
Detectives seized a 9mm Ruger pistol from Thompson.
"You're going to have potato salad 360 degrees from the muzzle," Hoelscher said. Of course, people haven't stopped trying.
Another favorite, often seen in movies and on TV, is to tape an empty plastic soda bottle onto the muzzle of the gun. I don't think this works any better than the potato technique. The
Insultingly Stupid Movie Physics Page points out that movies, in general, tend to grossly misrepresent the effectiveness of silencers. In real life they don't silence guns as much as they do in movies. (I should note that I've never handled a gun, so I'm relying entirely on the word of other sources here.):
Cutting sound intensity in half only reduces the relative loudness by merely 3 dB. This would be barely noticeable. A good set of ear plugs typically reduces noise by about 30 dB and so, would reduce a muzzle blast from 150 to 120 dB, still a very loud noise. We estimate that the innocuous "fut" sound made by a movie silencer is roughly 50 dB 7, a whopping noise reduction of 100 dB from the dB level of a muzzle blast! In other words, a silencer has to reduce sound intensity of a muzzle blast by a factor of 1010 to give such a low relative loudness. This can be done with a very well designed and precision made silencer using subsonic ammunition. However, even commercially available silencers are more likely to give a reduction of 30 to 40 dB similar to ear plugs, than the incredible 100 dB reduction frequently portrayed in movies, especially when used on high-powered rifles.
(via
David Emery)
Comments
Then again, the real sound would probably rip apart most speakers.
Errr, what does this mean?
Does he mean 180 degrees (away from the gun) or does he mean 360 degrees (back at you) or does he mean a spherical smattering?
Most of the noise from firing a gun comes from the speed of the bullet (if it goes faster than the speed of sound, then you get a nice little sonic boom) and from the explosion of all the combustion gases. Suppressors generally work in one or more of several ways: they draw out the time that the combustion gases expand, they slow down the bullet itself, or they use baffles to break up the sound waves. A potato might slow down a bullet a little, but only if it was already going rather slow, and so it would be rather pointless. It wouldn't have any effect on anything else, though, unless it just blocked off the muzzle enough that the gun itself explodes. Which would be a tad counter-productive, I think.
On a low-powered small-caliber weapon, a well-designed suppresser can actually reduce the sound of firing to very low levels as shown in the movies. But most of the time (especially with high-powered guns, like rifles) you're still going to have a loud bang that everybody in the area will notice. In those cases, the suppressor serves more to make it harder to tell where the shot came from, rather than to hide the fact that a shot was fired. It also helps save the hearing of the shooter, as otherwise firing off a fully automatic weapon in an enclosed room can be a bit overwhelming.
Of course, then there are Hollywood's ideas about recoil, and explosives, and camouflage, and. . .well, just don't go using movies to work out the details of your bank robbery or invasion plans.
First, it does have to be a low caliber weapon to have any real affect. Twenty-two caliber works nicely, though a .38 is also passable. When I say passable, I mean that you could fire the weapon in a house without a gunshot being heard throughout the neighborhood. However, if one is outside then there are no additional walls to help absorb the amount of sound that is made, limiting the usefulness of the "silencer." I have no idea what the decibal levels are, but there is a significant noise reduction. (And yes, before you ask, I obviously lacked quite a bit of sense when I was younger.)
Second, the technique is really only good for one shot because the bottle really does nothing more than trap the sound inside. As soon as there is a hole the sound "escapes." Therefore, unless you plan to carry enough pop bottles around with you to muffle the sound of every shot you fire, again the technique has limited usefulness. Oh, and by the way, only 2 liter bottles can be used. Twenty ounce bottles don't have enough volume for the gases to expand, their bottoms are too reinforced for the bullet to pass through without shattering the bottle, and the distance from the muzzle before the bullet hits the bottle is too short. As a result, a 20 oz. bottle will explode long before the sound waves are blocked.
Lastly, you can't aim the dogon thing. Let's just ignore the affect a 2 liter bottle has on your gun sights. More importantly, no matter what you do there is a certain amount of random deflection whenever a bullet hits any object, no matter how soft. Obviously, the bottom of a pop bottle is hard enough to create at least some significant deflection. As a result you can't hit target reliably even as close as 1 foot away.
So basically this technique is only useful if you use a small caliber weapon indoors and are not concerned about hitting your target. Not what I would call practical.
Man, I'm glad to learn that's wrong.
I would have been so embarrassed!
I once had a cat that was possessed by the devil, so I took it out back. Tied him up.
Got my .22 bolt action rifle, stuck a potato on the end and shot him multiple times.
The potato did a fine job suppressing the rifle, but
there was still a sonic crack.
The neighbors however did not notice any rounds were fired.
Why don't you just go to YouTube, if you have never handled a firearm, and see the Pillow silencer, or ask a veteran who has used or at least seen a demonstration of a silenced weapon? Silencers do in fact work; but it depend upon where you are as to whether they are legal.
Standard military and police silencers are so effective that all you hear is the bolt functioning, with many firearms with the proper loads.
1) Going to a small caliber has very little to do with it. In fact, most .22 loadings have a high velocity, so they emit a "crack" as they create their own sonic boon into the atmosphere.
2) It is the velocity that matters; stay below the speed of sound, or around 700 fps or lower. In fact, the .44 and .45 calibers make excellent candidates in a silenced weapon. And .30, even .50 caliber rifles use silencers in certain applications. Big, heavy, slow bullets will carry a long way while being very silent. In Viet Nam and elsewhere, certain troops carried silenced .45 ACP "burp guns" (among other types) where the operation of the bolt slamming back and forth was louder than the report of the big, slow bullet leaving the barrel.
3) Revolvers have a gap between the cylinder that holds the bullets and the barrel; so the gases escape there. Semi-autos handguns are employed for silenced firearms; and certainly any rifle (with proper loads) can be silenced since the bullet is inside a chamber when it fires in both cases. All the gases go out the end of the barrel, of course, where the silencer is affixed and the packing material and construction of the silencer slows and diffuses the gases that make the loud report.
The movies do in fact misstate and exaggerate almost everything - including what the authors of even fiction books have put down - for sensationalism and because the printed word has a different way of conveying a message than the printed screen. For instance, it is almost impossible to get a car to explode in a fireball from impact of a drop over a cliff; the gasoline is not vaporized sufficiently from the sudden impact with a hard object. How many accidents have you seen where a car exploded as it collided?
But since this is a myth-buster site, I think the posters should be more careful in expressing opinions not based upon any real world experience, with all due respect.
:cheese: