I have 3 similar guns that proved to be a bombs as well see the failure analysis thread. Two exploded immediatly, and the other took probably 20 shots (until hairspray chemicals worked the glue from the tape)

Parts:
1 2 Liter bottle
2 Pringles cans
Cotton balls
Packaging Tape

I drilled a hole in the bottom of the pringles can just big enough to get a 2 liter connector (without a cap) to fit. After it was in, I screwed the cap on from the inside of the can to secure it. After removing the bottom of ...

It won't do a thing, not with pvc nor a 2 liter bottle.
Also, guns wrapped in duct tape are more likely to explode.
(If it was strong it wouldn't be wrapped in duct tape in the first place). Same reason people who wear hats are more likely to get skin cancer.

I made a gun out of a UTZ Pretzel Jar, 2 Liter, and a Metal Pole from a pinball machine (leg).

A strawberry was loaded, but the explosion was enough to shoot the barrel off. Somehow, the pretzel>2 liter connection held perfectly.

2 Liter Bottles > Strong
UTZ Pretzel Jars > WEAK
Duct Tape > Weak ...

I decided I had nothing better to do that figure out a way to remotely trigger my gun, and I mean remotely.

Well I got a small wireless webserver all set, which is hooked to my pneumatic cannon's solenoid. There is a webcam & video streaming service installed as well.

Completing my solenoid ...

I made a quick physics calculator in PHP.
All numbers given will never be reached because of air drag, but they can give you a rough estimate. This is all for fun.

Part 1: (shooting gun straight up for simple calculations)

http://gamerssoft.com/?page=spudcalc

Part 2: (using part 1's info to ...