i see, but what i say is make a machinegun with standard parts; if you simply close the pilot area of a qev and put pressure there, if the piston is oringed, it is a machinegun. the rest is loading mechanism.

Finland66:
In theory it will work, but in real world a little variation on the dimensions and spring force may be the diference of working or not. why dont you start with standard parts?

JSR:
Not posted here yet, but soon will...
About the magazine, i'm in the second try (the first did not work ...

yes, the port diameter needs to be close to piston diameter. My configuration is 19mm diam piston and 15mm diam seat. The rate of fire can be controlled with a asmall ball valve on the input.
In the first video i used a regulated to 100 psi source and in the second a 850psi (co2 unreged) source ...

well, i built a variation of this concept some time ago and it works fine. The diference is that my trigger is a valve in the pilot area. The spring that i use make the valve opens at 50 psi, but with a stronger spring you can make it open at higher pressures. The inverted sealing face is not a ...

even if it is 500psi, 50ml chamber? .50 ammo

hello to all,
i m building a semi auto and the reload system will be like picture 1;
the question is: will it add a vertical recoil to the gun?
if i put a simple hopper like in picture 2, will be less recoil?

i have a co2 fire extinguisher 6Kg, and use it to fill 20oz painball tanks.
palmers reg fits paintball tanks trheads, and fill stations fit fire extinguisher; if u want soda stream, at palmers they have all adaptors you need; also beer keg cilinders are normaly same thread as fire extinguisher ...

i think copper pipe is ok for what you want. type L or K can hold 500psi without problem;
exemple:
http://www.spudfiles.com/forums/viewtopic.php?t=6013&

remember your system is as weak as the weaker component, everything must be rated to the desired pressure.

there are regs at palmers pursuit ...

About the reg, i think palmers pursuit female stabilizer is a good choice. there is a low pressure option 0-200psi. whats your source of pressure?
i do multishot this way: make a self closing piston valve (put a spring behind the piston) and fill from the chamber. the piston need equalization hole ...

Im buying this one:

http://www.ebay.com/itm/390478816145?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

The seller told me that it can handle 10MPa (1450 psi); what you guys think?
The thread is G1/2 (cilindrical bsp i think.)

About the o-ring, if you keep it very lubricated, i think it would ...

hi guys,
i found ptfe (teflon), nylon (polyamide), and did not find hdpe; i rethink the design to get more shots, so i´m thinking in 400 psi and 100cm^3 chamber (but i also want to use high pressures sometimes...) i think a 20oz co2 paintball tank could give me arround 90 shots at 400 psi; but will ...

i could use nitrogen, did not buy the tank yet; :)
i´ll search for teflon and hdpe to buy, nylon i know that i can find. a nylon piston without o ring will seal? will it stand the impact when the valve opens?

And what about wall thickness, i´m afraid... will it explode like a grenade? :)
Thank you ...

Technician1002, so the original draw will open without problems?
About the chamber you mean use a volume that alow a bigger pressure drop in the chamber to save gas?
Sorry, my english is bad, i dont understand what you say about single shot orings; thanks for helping!

velocity3x
i read this about ...

it will be much better if i could do this, but i ll have to build a check valve in the piston, or between the pilot and the chamber... the pieces will be small and the check valve seal will be a problem, cos i cant find a o-ring that small; if i use a piece of rubber, i think it will be a problem ...

you mean something like this?