Hey,
This is my golfball gun I made.
http://www.instructables.com/files/deriv/FCL/0ONC/F5Y3KXLX/FCL0ONCF5Y3KXLX.MEDIUM.jpg

This beast is capable of shooting a golfball over 500yards.

Just check it out here for step-by-step instructions how how to make it:
Golf Ball Gun!!! How To Make One That Can Shoot 500+ yards! - Instructables (http://www.instructables.com/id/E77FEVOF5Y3KXN5/)

This is mine, I am the original author and builder of this spudgun/golf ball gun. For more information please visit www.spudfiles.com I am a moderator over there under the user name MrCrowley

Possible potential for launching a hollowed out projectile with something slightly nastier than wound elastic perhaps. Of course obvious danger would be the "capsule" prematurely separating/exploding (depending on the payload) in the barrel.

I'm gonna take a good interest in this one. Perhaps I'll get some real world testing done

How long before we start talking about using mercury-filled golf balls?

Now the hard part. Making the thing reasonably accurate. I'll have to investigate your website for further information. However, I would think a nice trip back to the old artillery manuals could be a start.

At 500 yards, we are finally getting to a distance of use. Much closer, and you can't get away from retaliation. This is intriguing.

Plumbers nightmare..I love it:)

As a kid we used to have wars with the tennis ball mortor type devices powered by naptha..this is much more useful.

Haha yeah, I just got back from America so I couldnt reply until now(im in NZ).

You wouldn't want to have friendly wars with this, you will die.

Yeah you could fill it with explosives, how is up to you but it could be done.

With a longer barrel, bigger chamber and a bit more air pressure you could reach 800yards, maybe 1000.

Make it big enough to send toys made in China over into Mexico.:p