Zer

I work on cars.

Shoots Nerf Pocket Vortex footballs about 140 yards at an angle. Runs off 12 gram CO2 cartridges.

Isn't CO2 a big problem for plastics though? The low temperatures that are required to make it work cause the plastic to become brittle. Which would cause premature breakage of the gun. Anything with that much work into it would be a pain to replace. A normal paintball air tank would probably be better for the gun. You might want to check with somebody a bit more experienced, but I'm just letting you know it is a possibility.

The operating pressure of this cannon is about 100 PSI, which is about a third of what the PVC is rated to. The temperature issue is neglible due to the extremely brief exposure to the CO2. It sees less than half a second of exposure to gaseous CO2, and the length of tubing running up to the burst disk is plenty of room to allow for sublimation if any solid particles of co2 tried to make their way into the PVC section.

The small co2 cartridges I use are only good for one shot because they are rapidly dumped of all gaseous co2. If I left it hooked up and allowed for the entire solid contents to sublime (by somehow leaving the trigger system "on" and keeping the burst disk from breaking), that phase change would result in temperatures about 75* below freezing. PVC exposed to that temperature would become quite brittle.

I can't possibly be the only one repetitively chanting "WRITE-UP! WRITE-UP!" can I? I love the idea of scenario nerf, even though a lot of people here don't usually appear to. I was going to make something like this for physics class and we were going to have fights trying to hit the other teams target, but this, this is SO much better.

The best I can do at this point is a CAD drawing

For a simple target gun you can use a bike pump and inline sprinkler valve type setup. Easy to do and much more reliable and efficient than a ball valve. Feel free to PM me for more info.

Here is something that's kinda like what you're talking about.

It uses the same projectiles but operates on a completely different concept. I wanted mine to require a two-man crew and a significant downtime for reload. That video does show a really interesting design capable of a very good ROF. That gun in the video utilizes a valved system, whereas mine utilizes a disk of material that ruptures at a fairly consistent PSI.


--------UPDATE---------

Finally range tested the gun. At about a 40 degree angle it shot 145 yards. It gets one shot per 16 gram co2 with a little left over, so I'm thinking a 12 gram will work just fine. Firing/pressurizing delay is about half a second.

82.5 feet average of three shots, horizontal, from shoulder level (approx 5') using Sonic Micros

Wow. Could you show a pic of those springs you were talking about?

I used two ACE #155s (if memory serves me right) and trimmed one down until it was able to cock. They are about twice the thickness of the stock spring and wound more tightly. Unfortunately they don't go all the way up the plunger due to coil bind. I'm losing about 1/4 inch of free travel after the point in which the springs have fully decompressed.

The new barrel is extremely tight on Sonic Micros, and I think this lends quite a bit to the range. It may angle up a degree or two, but the body of the gun was horizontal during testing.