hello. i ordinarily force carbonate my kegs, but i'm preparing to age a dubbel for about 6 months and would like to prime this time. my question is this: why is less priming sugar required when kegging than when bottling? i've been brewing for about 10 years and have never seen an adequate explanation. i do not buy the explanation regarding headspace, since, while the headspace in a keg is large, it is roughly proportionate to the headspace in a bottle, given the greater total volume. it seems to me that for a given volume of beer with a given yeast count, a quantity of priming sugar should yield the same level of carbonation regardless of packaging. is there something in the cooperation of yeast when in a larger volume (like the keg) that i'm not considering? the last time i primed a keg using the prescribed 1/3 cup, the beer was undercarbonated. has anyone had this experience?