I have been working on a new project for a friend who owns a T-shirt shop who wants a t-shirt launcher.
I have most of my design figured out after reading as much as possible on here with what is available to me and my budget. I will list the specs and if im just completely off my rocker let me know, my primary builds are custom AR15's and AR10's so this was new but fun for me.
I will be using 3" SCH 40 PVC for the barrel and chamber, 6" chamber and 14" barrel connected with a 1" Modded Orbit sprinkler valve triggered by a high flow Air blower. There will also be a 120 PSI blow off valve installed in the back of the chamber for safety if the regulator was to fail.
Now the original plan was to use a 20oz CO2 tank for the air source but I think it would be better for the the ability to get more shots from one tank and not have to worry about the CO2 freezing anything vital. So I am now going with a Ninja Aluminum N2 Paintball Tank - 48ci 3000psi because it has the ability to be adjusted down to 450 PSI with the built in regulator and shims.
The tank will be connected at the front end of the chamber at the bottom of a 2" SCH 40 PVC T fitting and 1/4" inline ball valve so I can turn the fill on to charge the chamber and turn it off when the chamber has reached the PSI level I want for that shot.
The problem I am having is finding a 2nd regulator to install inline with the tank to bring the PSI down to 120 or so. Or do I even need to reduce the PSI from the tank any further?
Also I am still trying to figure out the piston and QEV to determine if one of those would be better for this and if I can figure out how to implement it in place of the sprinkler valve.
Any help for this noob would be great.
Here is what I have drawn up for the cannon. Any suggestions on something I might have screwed up?

