Here are some damage pics. I was shooting at a box fairly firmly stuffed with a sporadic mix of newspaper cardboard and low and high density Styrofoam.

The initial shot was a firm foam ball followed by a soft foam ball that was slightly heavier, then a regular golf ball.

All shots were at 80 psi ...

My two criticisms would be that your valve is too small for your barrel, while your chamber is at least double what it "needs" to be. Nothing wrong with the latter in terms of performance, but you get extra noise and pumping effort (irrelevant if you have a compressor really) for relatively little ...

So ideally I should have put the valve where it is but have used larger elbow sand delivery piping. Right?

About the barrel sleeve, I thought you had it set up to go in from the muzzle and were using the male pipe fitting on the muzzle to lock it in place, which might work but you'd have to flare ...

I like the idea of the interchangeable sleeve! Seems like it would be faster than unscrewing and re-screwing barrels.
The canon doesn't honk unless I fire it at 30 psi or below. And I don't really ever do that, I just noticed it when I was trying low pressure dry fires to test the integrity of the ...

All dry, tested, leak free and ready for fun!
Thanks for the help people!
Now..... to build a piston cannon

Thanks for the advice! And also, yes I totally ripped off your QDV with the plan.
Kudos on that design by the way!
Love the linear, self contained design!
I have still got soooooooooo much to learn! I'm just glad that I found this site! So many great thinkers and imaginative designs.(you included ...

sorry, I had to resize

I had an idea that I thought might be fun and I thought I would share. Basically choadish little launcher that would fire ping-pong balls.
The body and chamber are a pair of 4 inch pvc reducers with just enough pipe between to join them.
The center pipe is big enough to accommodate a ping-pong ball ...

Update!
I got the barrel made.(had to use 2 layers of schedule40 sleeved inside one another)
Also got the chamber assembled. I was able to get some 4 inch pipe for this so I was able to cut down the chamber length.
I'll probably head to Home Depot tomorrow and get the few fittings and the ...

Thank you for the fast replies.
I will not be using any Non pressure rated parts, so don't worry about that.
I cant find the SDR-21 anywhere nearby but will call around again on Monday before gathering materials just to be sure. :happy7:

Also, Just to make sure, I do need to use two layers of ...

This is my first post, so let me start off by saying hello to everyone. I'm very happy that I found this site and have been pouring over a lot of the information that is available here. Previously, I have made a basic combustion cannon with a grill piezoelectric ignition from PVC. And a large ...