SpudFiles

I'm making a qev semi auto gun, I was thinking of either sks or ak-74 with folding stock.
I want it to be set up like the image below

Would that work?
I'm propably gonna use a co2 quickchange adapter and then a normal ordinary paintball regulator, as that seems to be the cheapest option at the moment. then comes a slide valve as a pilot.
Anyone know to how much psi I need to shoot around 300 or 400 fps with 6mm 0.20g bb's? Also, how many shots would I get with one 12 gram Co2 cartridge using 6mm airsoft bb's.
and how big should I make the firing chamber?
The barrel length is roughly 40-50 Cm
Thanks in advance

Nice drawing

It's some what ok.. Good thing you are thinking about using qev and slide valve. My main concern would be the co2 in that position, you could end up getting liquid co2 in the system. Co2 bottles should be used upright, they contain liquid that vaporizes to high pressure.

You shoud have a small chamber or that 12g cylinder is not going to last many shots. I would use normal sized paintball bottle. Co2 12g cartridges cost also quite much compared to using larger reusable bottle.

0.20gram bb is very light, I dont think it need much pressure, so you shoud find a low pressure regulator for the co2. If you use high pressure I think qev is not good because it lets the whole chamber empty each shot. Hammer valve could work but it's lot more work..

GGDT is a great little simulator that will allow you to estimate parameters and performance.

Also, you do know MS Paint was a word function, yes