Tips on quick exhaust valve (QEV) paintball gun?

Cannons powered by pneumatic pressure (compressed gas) using a valve or other release.
AK47
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Hey Spudfiles,
I've been making pneumatics for a while, and recently I've been revisiting paintball guns. Keeping in mind that in my area, no paintball parts are available, is there any tips / tricks or problems with a design using a QEV and slide valve connected to a CO2 bottle for a semi-automatic paintball gun? I am hoping to use a pretty simple T-joint, spring loaded clip for loading, any thoughts?

EDIT: Typo
Last edited by AK47 on Mon Nov 25, 2013 9:02 pm, edited 1 time in total.
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cammyd32
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Spring loaded t joints don't often work all that well, you will probably want some kind of blow forward bolt or the like to make sure it loads properly, without one you will probably get double feeds every few shots, also you would probably need a reg somewhere in there, paintballs fired from a QEV setup at unregged co2 pressures are probably above and beyond safe muzzle velocities, lastly you will probably want an expansion chamber for the co2, so it doesn't freeze up on you.
Apart from that, yeah it's a good design, and has been proven to work well in the past, :)
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jackssmirkingrevenge
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You need to be using low pressure, remember that in a "tee mag" the burst of gas tries to squash the projectiles in the magazine:

Image

Too much pressure and it will burst the paintballs. Also hurt someone :)
hectmarr wrote:You have to make many weapons, because this field is long and short life
AK47
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jackssmirkingrevenge wrote:You need to be using low pressure, remember that in a "tee mag" the burst of gas tries to squash the projectiles in the magazine. Too much pressure and it will burst the paintballs. Also hurt someone :)
I have done some controlled tests without a QEV setup and the pressure is definitely enough to burst the painballs but my hope is that the restriction of pressure provided by a smaller volume of air (courtesy of the QEV) in combination with some room to expand will eliminate this problem. In truth I will probably end up using a 'blow foward' system like that which cammyd32 suggested.
cammyd32 wrote:paintballs fired from a QEV setup at unregged co2 pressures are probably above and beyond safe muzzle velocities.
By safe muzzle velocity, are you referring to a velocity that is 'safe' for what is being shot at or something else like what the setup can handle safely?
Last edited by jrrdw on Tue Nov 26, 2013 8:44 am, edited 1 time in total.
Reason: Double posting.
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jackssmirkingrevenge
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AK47 wrote:By safe muzzle velocity, are you referring to a velocity that is 'safe' for what is being shot at or something else like what the setup can handle safely?
The first one.

Exhibit A, courtesy of MrC:

[youtube][/youtube]
hectmarr wrote:You have to make many weapons, because this field is long and short life
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