hello, i made a 4 1/2 foot pvc cannon a few weeks ago. the problem is that i used celluar core for the chamber, the rest of the gun is pressure rated to like 260 psi. it is a combustion cannon. ive wrapped the chamber in duct tape 6 times, and im going to cover in in burlap as well.

i know that no pvc cannon is "safe", ive shot this a few times with minimal propellant. do you think i should just scrap this, or is it good enough?

Step 1, Yes, Scrap it.
Step 2, Stop sniffing the glue, and purple primer
Step 3, buy REAL guns. They are much more fun.

The above holds true for Airsoft as well.

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"Gutter is a tool"

Tired of how people view your states gun laws, hit your government where it hurts, take your tax dollars and leave.

i have 3 milsurps already, including a 1903. this cost me $25, i can shoot whatever i want out of it, assuming its not a massive pipe bomb waiting to happen.

as for airsoft, i love it

We have a few spud gunners here.
I'm sure one of them will speak up soon.
I would have used Sched 80 seamless steel for a combustion cannon but that is me.

And I agree with the Air soft comment.
If you really love to shoot at live people, you have serious mental problems.

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This is so easy, If my dog had thumbs, He could do it!

U.S.N. Retired 1985-2005

LOL! Potato guns are fun too! They feel like launching a mortar to me when put at a high angle.

I can't help you with your construction question though. Just be careful.

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Minds are like parachutes. Just because you've lost yours doesn't mean you can borrow mine.

Work good at getting your point across to annoying neighbors, a 1/4 a mile away!

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The Red Bearded Kraut

Spud guns are great fun. I built a pneumatic one years ago using an electronically operated lawn sprinkler valve. We usually use it to launch corn cobs a few hundred feet.

I'd be crazy to answer your question though.

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I'm the only guy in the world who has to wake up to have a nightmare.

I used Schedule 40 ABS.

That and cheap hairspray is big fun.

Watch out, you could attract the attention of BATFES!

Bureau
of
Alcohol
Tobacco
Firearms
Explosives
and
Spudguns



Snotsucker

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"keep your booger hook off the bang switch" - rustybuttplate

"Specialization is for insects." -Robert Heinlein

NRA Member

Im just going to wrap it in carpet and sheet steel, the barrel is where all the pressure is going anyway

I would scrap the chamber. I use sched 80 and a BBQ igniter to fire. Hair spray is a good fuel. Do know use mixed gas for any reason, or we will see you on Youtube blowing your face off. Mine has an accurate range of 150 yards.

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Gulf of Tonkin Yacht Club '70-72
GMCM(SW) USN 68-89
1776-2012 USA RIP
President NM MILSURPS

PVC is cheap and body parts are expensive.

I've built a few pneumatic cannons too, and I wouldn't make any part that will be subjected to the pressure out of less than Sched 40. I'd have gone to Sched 80, but the sprinkler valves I had were only rated to 125psi.

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A local guy lost a testicle to a spud gun. He used an 8 or 12 inch pipe for the reservoir, and a whole can of hair spray. The end cap blew off and hit him where it hurts. Just a thought, but I would rather reload real ammo. People are still talking about his accident, behind his back, 35 years later. But good luck. Keep us posted.

WHAT??????

Son you need to learn some basic 10 grade highschool physics.

The barrel is the weakest point as it only releases the pressure. It starts high and drops fast.

Your Chamber makes and takes all the presure.
It has to be the strongest part of the gun.
It must be able to SPIKE from atmospheric pressure to several hundred to even thousands of PSI in less then a second.
The initial flash is tremendous pressure.

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This is so easy, If my dog had thumbs, He could do it!

U.S.N. Retired 1985-2005

+1

Barrels are just channels to stabilize rounds. The receiver takes all the pressure, and it takes the shock-loaded pressure, as Burner said. That's why you see rifles with big, thick beefy receivers and really thin barrels, comparatively.

For every inch that round (or potato) travels down the barrel, pressure decreases sharply, because you have that much more space in the area behind the projectile. Same force + more space = less pressure. It's the difference between having 10 pounds behind a needle and 10 pounds behind a railroad spike. The needle will have a much higher PSI than the railroad spike because of the surface area.

Also, that's why engines aren't massively tall. All the pressure (power) comes initially, and the piston only travels far enough to spin the crankshaft. Anything else is lost pressure and therefore lost efficiency.