Originally Posted by Lou
properly filled bottles will definitely be better carbonated... the CO2 fills the headspace first...then when the pressure builds up to a certain level, the CO2 starts "overflowing" from the headspace into the beer, causing carbonation. too much headspace makes it hard for there to be enough CO2 (especially in a short period of time) to overflow into the beer.
Don't want to be picky here, but the CO2 doesn't overflow from the head space. It simply doesn't go out of solution if the ambient pressure (pressure in the head space) is to high. There are charts that tell you what pressure of CO2 is necessary to keep a certain amount of CO2 in solution. If the CO2 level in the beer rises, some of it will go out of solution and increase the pressure in the head space untill equlibrium is reached.
Actualy CO2 constantly goes out of solution and back into solution. If both flows are the same equlibrium is reached.