A while ago I caught a random vid on youtube of how to make the bottle cap shoot off a water bottle :http://fr.youtube.com/watch?v=bKrWhB_IPJU&feature=related
(Not the original one but he might be the son of a woman in another random link pic in a previous topic I posted).

The thing is I've been doing these for a while and they go off with a real POP! And the top shoots like a champagne bottle! (Sometimes too loud)

Deer park contoured ones seem to work best when twisted into two halves while squeezing the bottom half into the top and really twist.
Seems like it would be a fun contest to see who can do it loudest.

BTW, I don't have a video cam but perhaps someone can make one as loud as I can (much louder than link) and add a SF's link on youtube.

Anyone tried this or want advice how to do them?

the water bottles from my old school where the best fort this, i dontthink the teachers thought it was as cool as we did.

people at my school have been doing this for a LONG time
and let me tell you, if ya get hit, it hurts like a b*tch

This kind of thing seems right up there on the useful scale with stomping empty milk cartons in the lunch room... ..but fun non-the-less

starman wrote:This kind of thing seems right up there on the useful scale with stomping empty milk cartons in the lunch room... ..but fun non-the-less

But you can't shoot anything with milk cartons. Also these eliminate the stomping motion.

Saturday I was at the 4H fair with my youngest nephews and 2 *Doggy* girls had a pro-choice tent set up right next to where we were eating...
(Funny coincidence) when I twisted it up it was a LOUD one.
The sheriff patrolling came over looking all around!

Also it's an interesting valve. The "Twist valve" It opens much faster than a sprinkler valve. Shoots the light top 30ft. sometimes too.

BTW the animals there were so well groomed it made me want to switch to maybe a fish only substitute. Even saw a pig that was smiling.

starman wrote:Also it's an interesting valve. The "Twist valve" It opens much faster than a sprinkler valve. Shoots the light top 30ft. sometimes too.

i think that's because the valve is the projectile, and due to the spinning motion imparted by the threads, the projectile is also kinda like the barrel

Those are fun, me and some of my friends have battles with them in the lunch room

I made one of these, but I filled it to about 120 psi with a bike tyre pump. The pressure is probably higher, and it's a lot easier to do. I managed to get the cap to fly about 100 feet on a good shot, and it was pretty loud considering what it was. The valve was on the cap though, and for that reason I wouldn't recomment shooting anyone that you like with it.