Energy density of propane is approximately 2.45 MJ/M^3 (according to online source). I think this figure would be useful in calculations...not too inclined to do it myself right now.

Instead of doing dual 4" piston valves, just use one. Since the barrel is 3" already, a single 4" pistol valve (I assume 3" porting?) will work perfectly with it. Sure, having two would potentially give you more power, but due to all of the elbows and crosses you would add into the system, it would ...

Paintballs are soft, and they would likely get smashed in a cloud or vortex setup. I think it has been attempted before.

a really tight fit is good. right? A loose fit is bad, because air can rush past the projectile, hurting efficenticy A tight fit is bad, because friction will greatly slow down the speed of your projectile You are looking for a firm fit. In my opinion, the fit of a tennis ball in 2.5" SCH 40 is the...

I realized that a mini-lathe is not worth much if you can't use it. And it is certainly difficult to effectively use it if you have metal stock that is too long. Thus, I have decided to invest in a bandsaw. I have heard very good things about the following two bandsaws: <a href="http://www.grizzlyin...

I might throw the laser on there just for fun. It fits pretty well in 1/2" copper tubing. Since the laser has a momentary push button, I plan to thread a small hole in the laser housing (1/2" copper tube) and add a screw. This way, I can tighten the screw to keep the laser on, and loosen it to turn ...

I seriously hope so... But there is nothing in the comments that would lead me to believe he was kidding. What led me to this conclusion was that he demonstrated an apparently knowledge in what was "wrong" with the gun (that is was "not" a Desert Eagle and was "not" a .50). Furthermore, the last co...

I am pretty sure the guy was kidding...

I'm definitely going to do some type of sight...I have a high power (50 mW) green laser that I could mount...that is probably overkill though. I'll look into sights, though I'm not sure how functional they will be. About sleeving the barrel: it really does not sag much at all, for it already IS a sl...

Updated 11/1/08; check original page for new pictures and information.

If you are looking to pressure pneumatics, why not buy <a href="http://www.amazon.com/Twin-Tank-Electric-Air-Compressor/dp/B000RL8CB6/ref=sr_1_3?ie=UTF8&s=hi&qid=1225502614&sr=1-3">this</a>...air compressor for only $1.31 sounds good...I am sure there are no hidden fees, like $170.00 mandatory shipp...

The only place that I have been able to find SDR PVC pipe is at some type of John Deere Irrigation store; you might want to try those types of places for the pipe. Be warned, the pipe is expensive; you buy it in 20 foot lengths, and I think the price was like $80 (can't be sure, this was a few years...

My recommendation is just to avoid keeping the PVC launcher outside. True, the tensile strength increases. However, if that plastic receives even the slightest bump, it can crack, causing painful (deadly) shrapnel. If you are going to fire a PVC spudgun, prepare it for launch inside. Go outside, sho...

I don't think Demon was being rude... I'm not sure if this is against the rules or not, but if I were you, I'd put the thing for sale on eBay and then make a link to it in your signature. I definitely should know whether this is allowed or not on this forum, but unfortunately I am not well-versed wi...

Pretty sure its 1/8" NPT...that is the common size on most blowguns of that shape. They have a 1/4" NPT inlet and a 1/8" NPT outlet, once you remove that little metal fitting.