Design opinion for pneumatic

[jackssmirkingrevenge]

wow yeah your right i have but i dont quite understand how to make one

Not even with this photo tutorial of a similar technique?

[whitexnightjp]

... ive been enlightened both now make sense ive even read through the second link you gave me and prob haft understood it now i do thank you

[Fish8myb8]

Thanks Poland.
I actually have been reading a lot on this site, I just have a lot of questions so that I don't assume something.

I wanted to build a piston because it seems that all the top guns have a piston-QEV combo but I really wasn't sure that I would get it to work, and that I would just have $50 worth of metal that's mostly useless. I read a lot of guides, a 2" PVC piston, the self-closing spring piston, the youtube video by MRR, inspiration from HEAL, but I picked QEV's to start with because of the Copperheads. Copperhead Prime I think it was?

My air source is my manual pump, should I still go through all the quick disconnect stuff? I already have a trigger I'd like to use, and it's a bit more ergonomic

[Brian the brain]

but no one know how much worse as no one compared modded and unmodded (AFAIK)...

Psycix and I did run some tests to compare my shatterhand to his " unmodded" QEV gun.

His gun has a very large reservoir and a longer barrel.

No wonder I got lower velocities, but I think we both felt it was because of the factors above, not the modding bit.

I have not noticed any performance loss from modifying a QEV.
Unless ofcourse your pilot closes before the ammo has left the barrel...

It is possible to shorten the time the QEV is open, wich makes it perform less, when you use a lightweight hammer without much force behind it.
This means it is at your control..

There is no noticeable loss because of the tiny EQ hole however.
I'd be surpised if a chrony would show any difference.

[Fish8myb8]

All I would have to do in order to be able to pressurize from the chamber side is poke a hole in the piston?
The spring and hammer valve assembly you have is to be able to fire more than one shot from a single tank, right?
Because I can't get to pressures like yours with the pumps I have right now, I doubt I can get many shots off 1 tank at 100-200 psi.

[POLAND_SPUD]

I would say it's completely up to you... personally I prefer QEVs as they are ready made and pretty cheap (they cost more less as much as fittings needed to build a piston valve)

I don't think you should build a semi right now.. first build a single shot QEV gun then you can turn it into a semi auto... semiauto guns use quite a lot of air so you need to have a good source of it

@btb

I got lower velocities, but I think we both felt it was because of the factors above, not the modding bit

well it's is not a matter of whether it has worse performance (it's obvious it has worse performance) but how much worse

[Fish8myb8]

Thanks again Poland.
I don't want to get into semi's right now. I already ordered a 3/4 QEV from McMaster. I just want to be able to fill it through the chamber. All I need is a very small equalization hole, right? I still want to use my same blowgun trigger with a low pilot volume.

[POLAND_SPUD]

yeah, also a spring to help teh piston return to closed position

alternatively you can open the QEV and remove the piston and find something else that can act as a piston.. well no one said you have to ruin the original one

[Fish8myb8]

Okay understood.
Thanks a lot for the help, Poland