If you go on youtube and just search carbide cannon, carbide, carbid even karbid you will see a ton of videos with this stuff. The majority are all in other countrys it seems the US is scared of carbide or we just dont know enough about it.
There are many in class rooms with kids they shoot stuff animals, foam balls, socks all kinds of things using PVC and the same stuff im using. One teacher used clear pipes and one used pop bottles ive yet to see any fail. Ive built about 15 little guns using 3/4" and 1" PVC and then ive built about 6 cannons 5 of them with 4" breech the last with 3" (in the video)
used an A700 camera wrapped around my neck hanging down so there is alot of my breathing, i think i was breathing right down on the microphone.
http://s5.photobucket.com/albums/y191/B ... d20234.mp4
Smaller cannon at the bottom is what i was testing today, i just took a guess on the amount of carbide powder and how long i need to wait for the reaction. The last few shots i shook the mixtrue up and waited slightly longer and the ball seem to go about 15 yards further.