Hmmm. Here goes it in a nut shell. CO2 in front of the valve after piercing gives high pressure CO2 on front of valve. Spring pressure in valve keeps valve closed as well as pressure from CO2. As you cock the rifle, the bolt drags the hammer back over the sear and when you close the bolt, the hammer stays back behind the sear under spring pressure. When trigger is pulled, sear drops, hammer slides forward and smacks the valve stem and quickly opens the valve (kind of bounces the valve and doesn't leave it open). CO2 escapes past the valve and through the top of the port in the valve body and is transferred through the receiver tube port through the barrel port and behind the pellet. The bolt doesn't allow the CO2 to escape 'backwards' and the pressure drives the pellet forwards. To gain more power, make the flow from the powerlet through the valve, through the transfer port more efficient. You can also increase the 'dwell' or length of time that the valve stays open by either lightening the valve spring or increasing the pressure on the hammer spring. I won't go on about mods, but efficiency is what it boils down to. Hope this helps.
