"Spud Guns" aka Potato Cannons, etc... (PIC HEAVY!)

[HotGuns]

Thanks. Being a machinist and having the right tools can be an advantage.

It has a 1.5 inch by 1.5 inch powder chamber in it so it really cant be overcharged due to the short barrel. Overcharging will just result in a huge fireball with lots of smoke. I think the most effective burn is right around 300 grains of powder. Lots of smoke and fire with enough noise to rattle the windows.
Its always a hit on the 4th of July. I live in a remote area with no neighbors so I can launch the cans anywere I want to basically. Those cans do kick up some water when shot into my pond though...

[DefensiveCarry.com]

[friesepferd]

yea those are a lot of fun. just be careful! many people use them with pressures too high for the material they used. i know more than one person who has gotten hurt

[P95Carry]

I have three - this pic is of the largest (2" bore) - but also made one with 1 1/2" bore and a small one with 1". All to same design. Schedule 40 pipe and fittings ... and found the 90º bend made for a better combustion chamber than straight pipe. I have a pic of all three but not handy.

Inside near reducer region, two crossed wires with 1/4" spark gap hooked up to piezo igniter - and barrel muzzle is chamfered 90% outside and 10% inside ... this cuts a good potato slug but slightly over size for good fit. Propellant is Starter spray (ether) - very reliable. Hair spray is just a loada mess to get the propellant gas - leaves all sorts of nasty residue.

Range about 200 yards - did once do chrono test and calculated ME - it was quite impressive - read potentially lethal blunt force trauma close up. NOT a toy tho well safe used wisely.

[22RSSIX]

We have made three of the "spud guns"

the first one just had a gas grill sparker and a lot of duct tape on the outside. we figured if it was to blow the duct tape would keep us a little safer.

the second one had two power washer handles and the gas grill sparker was placed in the trigger of the rear handle.

the last one was an air spud gun. we got a brass valve, electric sprinkler valve, 3 nine volt batteries and a brass air hose connection and a electronic button. The chamber was 3 inch reduced to 1 inch for the barrel.

the sprinkler valve was rated for only so many PSI so we charged the air compressor to the max PSI for the valve.
all assembled like this.
aircompressor connection---brass valve---pvc--sprinkler valve---barrel.

It was fun, we did some stupid things with that one...

[Kerbouchard]

Pete, when you decide to start mass producing those things, let me know...I'll go ahead and put in my order.

[allenruger]

Wow! Now I could have some real fun with that. Nice work.

[Pete Zaria]

I have three - this pic is of the largest (2" bore) - but also made one with 1 1/2" bore and a small one with 1". All to same design. Schedule 40 pipe and fittings ...

Nice work, looks like a pretty clean and reliable basic launcher.

Remember, Sch40 is just a wall thickness, NOT a pressure rating. Most of the pipe they sell at local hardware stores (Home Depot, Lowes, Ace, etc...) is Sch40 NSF-DWV (Schedule 40, Drain-Waste-Vent, not safe for pressures above about 75psi). This pipe is OK for hairspray/starter fluid type cannons since they produce a MAX pressure of 80-something PSI (unless you use oxygen enriched mixtures as I have) and only for a split second at that. In order to actually be pressure rated, the pipe needs to say "NSF-PW" followed by xxxPSI.
Your bell reducer and end cap assembly are NOT pressure rated parts, but they're OK for aerosol cannon use as mentioned above. Don't burn more exotic fuels in that gun.

I prefer ABS pipe because if it DOES fail, it tends to "rip" open cleanly and doesn't throw any fragments or shrapnel around. I've actually tested this pipe to failure (dry ice, anyone?) to see what happens and I feel pretty safe firing the cannon from the shoulder now. :)

Pete, when you decide to start mass producing those things, let me know...I'll go ahead and put in my order.

I've seriously considered building them and selling them on eBay, the only thing stopping me is the potential legal responsibility.

According to the BATF, gas-fueled launchers like this are NOT considered firearms or destructive devices, and are legal for use on private land as long as you're not damaging anyone's property, etc....
They become illegal when you use an incendiary or flaming projectile, a solid propellant (such as black power, gun cotton, etc...), or point it at someone.
Also, the odds of any given LEO knowing the laws about such devices is probably low, so if you build one, I suggest printing up a copy of the relevant laws in case you get a visit from the boys in blue. Around here they don't seem to mind spudguns but I'd bet in an urban area it'd be a different story.

If you'd be willing to sign a disclaimer releasing me of ALL responsibility, I'd happily build you one (for, say, whatever parts cost + 25%). Let me know if you were serious

Peace,
Pete Zaria.