As it was a perfect day here, I pulled out this project again and shot a few shots with my 22 year old son, hehe. And there is stillthe hunt for perfect projectiles. As we use the Dutch 40mm white PVC pipe.......

1. Film canisters, which you need in huge quantities anyway for using with Alka Setlzers. These are a very tight fit so the closing edge might need a tiny bit of sanding.

2. A modification of the perfect Guhl caps (see below): fill with water and find the perfect champagne cork to close it **)

3. (for the pro's) D-size batteries. They weight about 135 grams. THIS IS DANGEROUS!!

**) I shot one of these straight up and it went way over the top of my house. My guestimate is 12 meters. Weighting 50 grams the potential energy at that point is h*g*m = 12 * 10 * 0.05 = 6 Joules. 6 Joules in kinetic energy is 6 = 0.5*m*v-squared, so v, the muzzle velocity > 15 m/s, > 55 km/h (35 mph) :-o :-o :-o