SpudFiles

i would want some help i was thinking if i had a chamber that 75mm in diameter and 50cm long and a barrel that was 50mm in diamiter and 1m long can that work

You would get a C:B ratio of 1.095:1, which is fine. What pressure are you wanting to run at? The higher the pressure, the smaller the volume if you want the same results as a low pressure high volume chamber. It should be fine either way though.

BTW, you work out C:B ratio by going:
(chamber) pi.radius(squared).height of chamber
divide by
(barrel)pi.radius(squared).height of barrel

pneumatic or combustion ? i think it would be combustion and for combustion thats a fine ratio if you don't want a large amount of power. make the chamber and barrell longer and you're in.