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john clements
10-25-2006, 10:16 AM
I had a crazy idea. Precharged airguns use compressed air from a pump or a scuba tank to fill a cylinder on the gun. Would it be possible to fill that cylinder from a Propane or Butane tank to give similar pressure? (I know nothing about the relative sizes of gas molecules). If so, would the gun work? And, if so, what would happen if you introduced a piezo spark at the instant the trigger releases the gas to fire the slug? It seems to me that the burn would greatly increase pressure and velocity.

There is probably some great big snag which I can't see but I have no doubt somebody cleverer will put me straight.

John Clements

JCHannum
10-25-2006, 10:25 AM
The pressure of propane or butane is too low to give an "air" gun much boost.

If a spark were generated in a space of butane vapor, nothing much would happen. An explosive atmosphere would have to be created by somehow adding oxygen. Then it would add propulsion to the projectile.

brunneng
10-25-2006, 05:04 PM
Basically you're talking about a gas fired portable nailgun. You could find those at any decently stocked hardware store. Change out the nail guide and fit a receiver and barrel from an airgun.

Of course that might qualify it as a firearm as it has enough force to drive a framing nail into a 2x4. Then there's the safety factor of using explosive gasses.

Kevin

Todd Tolhurst
10-25-2006, 05:18 PM
According to Federal law, the term "firearm" means
(A) any weapon (including a starter gun) which will or is
designed to or may readily be converted to expel a
projectile by the action of an explosive;
(B) the frame or receiver of any such weapon;
(C) any firearm muffler or firearm silencer; or
(D) any destructive device. Such term does not include
an antique firearm.

So, force isn't a criteria, but whether or not the burning gasses are are an explosive is.

IOWOLF
10-25-2006, 07:00 PM
It does mean it is a firearm.

The Barracuda had a ether charge and Gave up its air gun classification even if it just used air and no ether.
Same goes for the Daisy V/L caseless "air"gun.

HTRN
10-26-2006, 04:25 AM
You might want to look into Tippman's "C3" pump action paintball gun. It uses propane combustion to propel the paintball - I'm not sure exactly how it got around federal laws concerning firearms.

On a side note, a good deal of the high energy airguns seem to be moving towards using C/A tanks meant for paintball guns, it's what I plan to use when I get around to building mine.


HTRN