Help with high pressure cannon

[spudkpi]

I am in the process of building a co2 regulated gun... I have all the parts to regulate the pressure but have no idea what chamber size to have. I want to make the barrel 1/4' ID so that I can shoot steel shot at very high pressure. I guess all I need help on is what chamber size to have, I will be building... or trying to build this piston valve I have a QEV ordered from online but the pressure only goes to 150 and I'm looking for this thing to rock some socks. Any help would be great. Thanks. And any tips on finding a 1/4" ID barrel would be awesome.

[MrCrowley]

We need some more information; how long is your barrel and what is your intended operating pressure?
What QEV did you order? Chances are it can take ~700PSI if it is made from metal. As for the barrel, try a hobby store or such.

Chances are your chamber would only need to be about 8" of 1/2" galvanised iron pipe.

[deathbyDWV]

Yep an 8"x1/2" pipe should be good... Unless you have a really long barrel...

[mark.f]

1/4" steel brake line has an inside diameter of 0.18", and is what most cheap BB guns utilize as barrels (1/4" hydraulic tubing). Go to autozone and they usually have different lengths behind the counter (ask).

Also, I personally have used a standard Detrol QEV at 300 PSI, but a piston is always a little sturdier than a diaphragm.

[spudkpi]

More or less this is the QEV i bought http://cgi.ebay.com/Pneumatic-Quick-Exh ... 3ca1f78e9c


However I am open to make my own piston 'T' valve which I have failed at before, but I think I could do it. As far as barrel length probably 36". The QEV I ordered says it only goes up to 150 psi so that is what I am questioning... can I take it higher or will I blow it out. And also.... where the hell do you buy steel shot? I have tried like Dick's hunting department and such but I cannot seem to find it. Thanks guys this is really helping.

[MrCrowley]

The QEV I ordered says it only goes up to 150 psi so that is what I am questioning... can I take it higher or will I blow it out

I'd feel safe at 500PSI with that. To be honest, at 500PSI, there are other components that would worry me more (blowgun, any hoses, homemade/modified) parts etc.

[spudkpi]

The QEV I ordered says it only goes up to 150 psi so that is what I am questioning... can I take it higher or will I blow it out

I'd feel safe at 500PSI with that. To be honest, at 500PSI, there are other components that would worry me more (blowgun, any hoses, homemade/modified) parts etc.

Thanks Crowley this helps.... but can you modify the factory QEV to go to higher pressure.... and just curious about how many shots would a 20oz paintball cO2 get outta this thing

[Patto]

You can take your qev to 500 psi without to
much worry no mod's required ,just don't run unreged c02 (800psi) also with your steel shoot try a bearing shop normally cheaper and a hobby shop for your barrel . I have the same setup at the momment running on 400psi not a problem and lots of fun, just need to finish the stock