Grenade launcher shell

[gint]

Hello. I am thinking to make CO2 powered grenade launcher shell. Something like this, but with bigger hole. http://www.arsenalguns.fr/images/Image/XMPB4.jpg Any advices? Maybe someone tried to make something simillar? I have turning lathe and i am thinking to try to use it for this purpose.

[PanzerFaust]

those xmpb4's rock! Mostly because the gas storage chambers extend almost the whole length of the shell. I'd like to see a longer version of that shell able to hold MOAR gas and MOAR projectiles. don't frak with the diameter of the bore unless you can do so without reducing the size of the gas reservoirs.

[gint]

I found this device. http://airsoftpacific.com/viewtopic.php?p=304689 Any one can say a little bit more about it? How it works? I need more information about mechanism which spreads CO2. What holds CO2 when it is filled with it?