Where can I find a 4" to 1.5" PVC reducer bushing? I have already been to my local Lowes and Home Depot but I found nothing. I know they exist because I saw another potato cannon made with one.

I have been trying to develop plans for a new spud gun. I am a little unsure if my calculations are right though. I thought of a 4 x 12" CC and a 1.5 x 60" barrel. I tried to do the math and I came up with a ratio of about 1.5:1. Am I close or way off?

Thanks everyone! This all makes sense to me now!

Thanks Pete. I guess maybe shooting for 700 feet was a bit too much. I don't want the gun to be very large. How do you do the math to figure out the ratio? I don't want to sound stupid, but how did you do the math to get the volume of the barrel? Maybe if I knew how to do the math for the ratio, I c...

Ok, I built a potato cannon before, but I want to build another and I need your help. I have a few questions about the materials to use and dimensions of the gun. I built my last gun and I had no idea there was a ratio involved with the combustion chamber and barrel. The new gun I want to build, I w...

That sounds cool, except the 10 foot barrel. I would like to keep the barrel the same length as the one I have now, just a smaller diameter, so how small would I need to make the combustion chamber? Merged: what fuel are you using? if yopur cannon is all pressure rated then try some starting fluid I...

Hows it goin? I'm new to the potato cannon world and I love it! I wanted some more distance with my gun. I was able to fire a potato 540 feet. I saw a kid fire one 740 feet. How can I get more distance? I have a PVC cannon: 4"diameter combustion chamber, 18"long and a 2"diameter barrel, 44"long. I h...