Re: fuel tanks and bullet silencers
Here's how it was explained to me. The noise out of the end of a gun barrel is the rushing gases expanding behind the projectile. That gas is what pushes it out the barrel. A little 22 revolver makes about as much ear damaging sounds as a .357 Magnum. Well, maybe not quite as much but spend an hour on the range without ear protection and your ears will ring for days.
A silencer can be made several ways. usually the inside of the barrel is tapped to accept the silencer which has its threads on the outside. BTW, this ruins a good weapon because the last half inch or so is ground away for the threads. All you can use it for now is wacking people or shooting your neighbor's cat which wails all night under your bedroom window!
Then the casing of the silencer is filled with an inner barrel slightly larger than the caliber of the weapon so the projectile doesn't get jammed on the way out. This inner barrel maybe fluted or have holes drilled in it so the escaping gases flow into the space between the outer casing and the inner barrel. The space between can be filled with insulation or some other sound dampening material. When the waepon is fired, the rushing gases flow into the space momentarily and as the projectile passes out the barrel, the left over gases ooze out the front of the silencer giving it that unique sound or lack thereof.
Now, don't go making one yourself as they are illegal in all 50 states, and besides you could blow your hand off or put your eyes out firing the weapon!
Simple yet so exotic!
