Spud Guns

02/19/10

First a serious note: If you're gonna do this, use ONLY Sched. 40 or better PVC. Else you will experience great suffering.

Spud guns are illegal in many states. They qualify as zip-guns, which is basically a weapon that uses a combustible propellant and a smooth-bore barrel. So this is basically a page to show you what not to do. That said, let's begin.

A few general comments are in order. We have tried many propellants ranging from deodorant, to ether, to WD-40, and have concluded empirically that hair spray is the most potent stuff you will easily find out there. Get whatever is on sale; it doesn't seem to matter if you're shooting Extra Hold or Regular. As far as ammo, spuds or other tubercles have proven best: they're inexpensive, easy to cut with the barrel, and make a good seal. Regarding igniters, we have tried a host of things, both internally and externally mounted. Piezoelectric BBQ lighters are useless because the electrodes clog up, making them very unreliable. The best solution we have found is to install a flint lantern igniter (a $2 part) in the combustion chamber's cap. This way it can be kept out of the propellant stream when loading, and it is readily accessible for maintenance. It also has the virtue of self-cleaning (by definition) so you get a good strong spark every time. Success rate with this method is basically 100% (failures only when flint is almost out), while piezoelectrics were 20% at best.

To load and shoot: place the projectile material on the ground and position the barrel vertically above it. Push down to cut the projectile. Using a suitably long broomstick, push the projectile through the barrel. Open the combustion chamber but keep it partially covered while your assistant sprays 2-seconds worth of propellant in the chamber. Promptly close the chamber, aim at what you want to destroy, and flick the igniter. Repeat as necessary. Note that for the greatest psychological effect, and to permanently instill the fear of god into your enemy, you should attack at night: the view of your gun's spewing flames will do the trick.

The big gun

Ingredients:

35 inches of 2.5-inch diameter PVC pipe.
2.5 to 5 converter.
14 inches of 5-inch diameter PVC pipe.
5-inch diameter coupling.
5-inch diameter cleanout with threaded plug.
Lantern (flint) igniter.
3-inch nail.
PVC primer and glue.

Assembly:

Bevel the business end of the barrel (that would be the end that your enemy is exposed to) both from the outside and the inside in a way that it has a "v" profile. This has 2 purposes: it will sharpen the barrel so that it can easily cut through things such as potatoes, and it will cause a cut on said potatoes that compresses the projectile to increase power and spell certain doom for anything that crosses your sights.

Drill a pilot hole diametrically across the other end of the barrel 2 to 3 inches from the end. Insert the nail and cut it flush with the barrel's outer surface (pix below). The nail stops the the projectile at the correct spot when you are inserting it, and prevents it from accidentally entering the combustion chamber.

Drill a 1/4 inch hole in the threaded plug and install the igniter.

Finally, clean, prime, and glue the PVC parts in the obvious order. You are now ready to take over any small unsuspecting country.

The Love Gun

The Love Gun came about when my girlfriend asked me to make a concealable spud gun for her. This was a bit of a challenge at first, but it worked out quite well. The resulting gun is extremely reliable, concealable (if you wear a cape) and incorporates advanced features such as interchangeable barrels.

Ingredients: