silencer?

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regre7
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Thu Dec 22, 2005 9:03 pm

I've been reading up on the theory behind silencers after seeing an idea about using one on a spud gun. From what I gather, the noise any gun makes comes from the hot gasses meeting the cooler air, and a silencer works by giving the hot gas (in a combustion launcher) more room to expand, thereby decreasing its temperature (Charles' Law) before it leaves the muzzle, which lessens the noise created.

Anyway, for a silencer on a spud gun, would a simple attachment on the end of the barrel (assuming the barrel is 2") consisting of a 2" to 3" increaser and about 6" of 3" pipe? Also, I've seen holes drilled in some of them, would this help?

Another thing, assuming the above theory/application is correct, if I were to somehow actively cool the silencer assembly (I've got an idea for water, hard to explain), would that make the silencer more effective? My theory behind it is (using Charles' Law again), if the temperature were decreased, then volume would decrease as well, reducing the amount of gas making noise.

Of course, if I had a longer barrel (to an extent), I'm pretty sure the noise would decrease, as more of the energy from combustion is used to propell (I can't remember if that has one or two l's, stupid fitness water!) the potato down the barrel.
irontree
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Thu Dec 22, 2005 10:44 pm

A real silencer has baffles that trap expanding gas and reduce the report. Something I tried that worked very well was to attatch a length of wider pipe with a few holes, and inside that a smaller pipe filled with holes. You can use some sort of fabric as a spacer. On my combustion (3'x2" barrel) I used a foot and a half of 3", and 2" on the inside. I didn't glue anything, so it was all wobbly and didn't quite line up, though the report was quieter than a pneumatic. Since my inner pipe was the same as my barrel, the shot didn't go far, but maybe you could work something out.
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boilingleadbath
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Fri Dec 23, 2005 12:56 am

*required post*
Depending appon where you live, a silencer may be illegal to posses.
Oh, and let's keep this a tecnical discussion, please... we have enough "lol, silencers are cool" threads already. (I think we have 3)
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julz
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Fri Dec 23, 2005 7:41 am

blb, yes, they are illegal in australia as well, thats ANY device designed to reduce noise.
regre7
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Fri Dec 23, 2005 9:58 am

For some reason the forums won't let me attach my drawing in .jpeg. Oh well, I'll try to explain it without it.

My idea is to extend my current 2" barrel by 1.5' (as it's already a bit short), drill holes in the new section., and use a 2" x 3" bushing with about 1.5' of holed 3" pipe attached to it as the silencer. However, to attach the silencer assembly, I would file down the stop on the 2" side of the bushing so it will slide on the barrel. It would be stopped by either two screws drilled into the barrel, but not penetrating the inside (preferable and aesthetic), or if all else fails, duck tape (unpreferable and unaesthetic, but popular here in the South!).

If all of the above sounds good, could someone enlighten me as to any special rules about extending a barrel? (I was thinking just take a 2" coupler and solvent weld the existing barrel to the coupler to the new holed extension.) I'm afraid the stop or something will catch the potato, which is bad because...
boilingleadbath wrote:the arora of a barrel is mutualy incompatible with the one of the fittings, and attempting to combine them will touch off a nucular reaction of the hydrogens, catalized by the clorine in the PVC. The yeild of this has been estimated at 5 kilotons for a female fitting on 2" pipe.
In truth, this is a major security concern; all of these components are readily available at your local hardwear store, and the device is fully capable of leveling a small town.
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Technician
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Fri Dec 30, 2005 8:50 pm

Correct me if I'm wrong here but isn't a lot of noise consistent with a lot of lost kinetic energy? If you get the CB ratio lower you should increase the projectile speed while at the same time eliminating the majority of the noise.

And if you do that you can still build a look-alike silencer for aesthetic purposes and still have top projectile speed.
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boilingleadbath
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Fri Dec 30, 2005 10:17 pm

Yeah, that's true technician. One can see the text of the burnt lakte (burntlakte.com) chamber:barrel tests to see just how quiet it can get - to the point where the projectile sliding down the barrel was the major sound.

However, that technique has it's limmitations - for instance, if you have gun with a large chamber, it's often impractical to lengthen the barrel to the point where it makes no noise. (of course, one could always use a larger diameter barrel, or just settle for a reduced amount of noise)
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