EMPyre,
When I started kegging many moons ago, I didn't read/follow the directions. They called for 1/3 cup & I used 3/4 cup dextrose to prime. I Let the keg set for a month and got super carbonated beer. I talked to one of the guys at a LHBS and he explained to me that you use 1/3 to 1/2 cup when kegging because that will get it "started" if you will. When you hook the CO2 up to drive it, while it's setting there hooked up, it will force some of the CO2 into solution and increase your carb. Since I naturally carb., I would put my beer in the kegerator and set the reg. for the style and hook it up to the keg. As the keg cooled down over night, it would force more CO2 into solution. Usually, by the second day, if I could keep my paws off of it, it would be carbonated perfectly. As with most of my responses, this has worked for me. I'm not sure if this explanation is correct, but it has definitely worked. Luck - Dwain