Spud Cannon Suppressor (CHEAP 'n EASY)

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
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Mr.Sandman
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Sun Aug 03, 2008 10:09 pm

thats not entirely true, on my bb sniper i have a silencer and it sounds like a low click instead of a loud snap
Yeah, it's that important.
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Sun Aug 03, 2008 11:38 pm

Looks like a good design. Maybe more baffles than pic.
It's really a matter of having enough baffles spaced properly and the diameter. Some professional one's have slanted angles creating chambers or cone shaped baffles with points inward (muzzle). Flat one's are ok just longer in length.

A Good idea (especially for smoothbores) is to sandwich a rubber washer (with slightly smaller diameter hole than projectile) in between two metal washers (with a bit larger hole than projectile).

About the legality of silencers on pneumatics, perhaps a way around issues, or to be certain it cannot be fitted to a firearm, is to permanently fix it to the barrel. Then possibly make the internals removable so it doubles as a shroud or suppressor. (That's what I'd do if I wanted one).
But probably it depends on your lawyer and what you were shooting I suppose.

Most of those laws are also worded that if you have the parts for whatever to be assembled= same as completed one. So stashing stuff unassembled is not enough. I've known three guys who got mandatory five year sentences for firearm charges (two involved just hunting).
So I just don't ever do certain stuff (like silencers).
Also the only reason the warrant was obtained for Waco was that they owned AR-15's and also ordered books on converting them. (sort of Like having parts)
Course it's different when it's a cult. :roll:

For mounting onto a metal barrel one way to avoid visible threading or a modded version, is to bore out the inside of barrel a fraction of inch deep, Thread the inside and build a bushing that screws in when the silencer is not installed. If it's smooth it won't affect accuracy. For many handguns the weight of a suppressor can cause jams though. :)

EDIT: This should've maybe been in How-to's.
Also the reason I've pondered silencers is for (Against rules to discuss) So for example if I was hunting (legally) with a bow and arrow and the [game] hears the string it might jump and be hit horribly wounded rather than where I aimed (dropping it quickly). But I won't mess with that idea probably.
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jackssmirkingrevenge
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Mon Aug 04, 2008 3:22 am

Some detailed information regarding the legal position of non-firearm silencers in the states can be found here, worth a read through.

As to the design that's the subject of this thread, I would advise against having baffles beyond the edge of the barrel, due to the fact that most spudders fire irregular and unstable objects out of their barrels that would start to tumble and potentially destroy the freestanding baffles. The same logic applies to shotgun suppressors:

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Mon Aug 04, 2008 11:41 am

i would also suggest adding something along the lines of a gas redirector (something that you would see on a Barrett M109, or other .50 cal bmg) this still wont 'suppress' the blast, but it will redirect the cold and warm gasses in multiple directions... remember; nothing can completely silence the sound; only make it less recognizeable. uk spudgunner is absolutely right; your cannon will still be pretty loud even after constructing a proper suppressor. no matter what you build for your spudgun; you will NEVER end up with a hollywood 'wisper' gunshot. lol

As stated earlier; it is extememly important to have the baffles lined up correctly...for my design, i suggested having the inner diameter of the baffles slightly larger than the potato cannons barrel. and the reason that i have a small amount of baffles is becasue the more you add; the more chance that you end up with mashed potatos inside your silencer... if not, you may end up with your suppressor shooting off entirely with the snagged potato. always be careful when attaching something to the muzzle of a potato cannon! :)

Ps. Jackssmirkingrevenge; thanks for the insight on placing the baffles overtop of the barrel!

here is a new design i am working on... the black is the original cannon barrel, the red is the PVC Suppressor and the brown thing is the potato :) i plann on drilling holes in the end of my existing barrel at select intervols (corresponding to the location of the baffles in the suppressor). because the holes that i am drilling are inside the barrel; i plan on using a file to smooth out the inside edges so that the sharp edges dont cunt into the potato while it is either being loaded or is being fired out...
to create the angled baffles in a cone shape; i was thinking that 2''to 3'' converters would do very well (they are allready round and fit snugly at both ends) i plan on making the expanison chambers much larger than what is pictured. the first chamber is likely to be roughly a third the length of the barrel.
Anyone have any suggestions on how to make it better?
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jimmy101
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Mon Aug 04, 2008 3:10 pm

So, if you did build it, <strike>did</strike> does it work? How much <strike>is</strike> do you expect the sound to be reduced versus the affect on the muzzle velocity?
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Mon Aug 04, 2008 4:42 pm

I would like to clear up a little confusion, to avoid legal repercussions.

In the state of Texas, ANYTHING THAT FIRES A PROJECTILE BY USING ANY SORT OF COMBUSTION IS CLASSIFIED AS A FIREARM. THIS INCLUDES DEVICES KNOWN AS 'POTATO GUNS'. Meaning, if you were to put a suppressor onto a combustion in Texas, you just made a Class III firearm.
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Mon Aug 04, 2008 6:35 pm

So, if you did build it, <strike>did</strike> does it work? How much <strike>is</strike> do you expect the sound to be reduced versus the affect on the muzzle velocity?
I wasn't asked the question but let me say, years ago I saw a homemade one, like I mentioned, mounted on a semi-auto .22LR.
With sub-sonic ammo (Below about 1140 fps) the only sound heard was the firing pin click and then the bolt and spring click-click.
Also a moment later a whomp (soil) or whack (harder stuff) the projectile impact. :shock:
With supersonic (several normal .22LR bullets) same thing only a moment after firing a cracking KaKrrrrr...of the bullet's sonic boom. Still much quieter (but distinguishable sound).
For it's size the .22 has alot of pressure. similar to a miniature .44 mag.
So I would infer any thing could be silenced equally (with a scaled up suppressor).
As for Lost velocity Probably significant to none. Since the suppressor is mounted on the end of the muzzle and there isn't any applied increase after leaving the muzzle.
If holes are drilled in the barrel then there will be loss similar to a shorter barrel. But it's not necessary to drill holes. 8)
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Mon Aug 04, 2008 7:47 pm

"So, if you did build it, did does it work? How much is do you expect the sound to be reduced versus the affect on the muzzle velocity? " -jimmy101

i built a cannon with a silencer that had the baffles in front of the barrel...it does work, but not as well as i would like. in the first post with two pictures the first one should work better (thats the one i am trying to build right now) it should work better becasue the baffles can make a more air-tight enclosure around the potato, however there will be slightly less speed to the spud becasue there is a continuation of the barrel but the pressure behind the potato is being let out (becasue of the holes drilled at the end)... but im hoping the drop is not too significant :)
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Mon Aug 04, 2008 9:19 pm

That is my worry, loss of power and speed. I'm now using tennis balls and they are designed to slow down by themselves. Well, I guess if I don't build one I won't be able to use my launcher very much. I'll try this weekend and let you all know.
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Ragnarok
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Tue Aug 05, 2008 3:59 am

ralphd wrote:That is my worry, loss of power and speed. I'm now using tennis balls and they are designed to slow down by themselves.
Anything will slow down by itself. :P

The question is whether you're trying to use the effect to your advantage, or whether you're trying to minimise the effect.
Does that thing kinda look like a big cat to you?
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Tue Aug 05, 2008 5:44 am

With combustions, the same logic of cooling down propelling gasses to reduce pressure and therefore sound applies, meaning use should be made of steel wool or wire mesh to fill the expansion chambers. Also remember that volume is very important, more important with spudguns than conventional firearms, so make the biggest suppressor body you're willing to live with.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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