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How Efficient> Full Auto Attempt

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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How Efficient> Full Auto Attempt

Unread postAuthor: svdesigns » Sun Jul 22, 2012 1:47 pm

Hi everyone just wondering on peoples thoughts on this setup. Basically the setup is going to be attached to a qev with a pop off valve set to 120psi. The piston blow forward bolt is a centered piece of 6mmOD 4mmID copper tube within epoxy molded to fit inside the brass tube with o rings. This sleeves onto the 4mm solid copper tube. as the qev goes off pressure pushes the piston forward loads the ammo into the barrel and about an inch of the bolt will enter the barrel (i feel the jams and bent bolt coming but the piston actually stays pretty straight and true) at the point it clears the 4mm tube and dumps the air out the inside of the bolt. am i going to lose a lot of force going through a qev and the blow forward mechanism? i feel like there is a lot of wasted air using a pop off valve as well. if only i could get a high psi rated spring i could lose the qev all together right?

does anyone know how much psi those chrome plated brass tubes can handle?(the ones u get at a hardware store, bunnings in my case)
right now everything is pretty much done, just waiting for some o rings and springs and i can test fire to see how it runs. anyone see anything that could use improvement off the bat?
Thanks.
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Unread postAuthor: jackssmirkingrevenge » Sun Jul 22, 2012 2:14 pm

A QEV can be converted into a pop-off with a bit of imagination and a strong enough spring.

Basically block of the pilot and fit a spring, feed air from where the barrel would normally would be, and bit the barrel where the chamber normally would be.

As to your blow-forward setup, looks like it can be shortened, and the diameter reduced, if your aim is to make it more efficient.
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Unread postAuthor: svdesigns » Mon Jul 23, 2012 3:23 am

yeh thanks for the input the reason the blow foward is so long is given the tools i have its the only way i could make it stay straight, also i thought i could ditch the qev and make the blow foward chamber act at the pop off itself giving it enough volume required to push the ammo out the barrel. the volume can be adjusted by spring length or stoppers anyway.
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