sounds a little bit like the syphon tube type co2 setups used on some old paintball guns, basically when co2 is compressed it turns to liquid (hence it being measured in ounces and not by its pressure, by running a tube to the bottom of a bottle you can get it to draw the liquid up and not the gas which is then expanded in the valve assembly to provide the propulsion gas, as I said this has been around for ages and is of little or no use in a pcp, I did see something about converting a crosman to run on liquid and it does indeed work in a more efficient manner than letting the co2 gas prior to using it, however there were stark warnings about the dangers of trapping liquid co2 in the gun or feed tubes.