Expansion chambers are used to make the fluctuating pressures of CO2 more consistent. All other things being equal, this more consistent pressure makes your shot velocity more consistent from one to the next.
More info near the bottom of the page.
CO2 (Carbon Dioxide) is under pressure in your tank and most of it is in a liquid form. As it moves in to your gun to shoot, the liquid changes to a gas. As this happens the pressures fluctuate greatly. Normally, the CO2 has ex
