I've been attempting to brew 2.5g batches, but my OG's are consistently coming up low. I use a 5 gal. cooler for mashing, and am pretty anal about temps and volumes. My grain is milled at the store, and I've considered that as the culprit, but I brew10g batches with friends and we get our grain from the same store and have no gravity issues. So I'm wondering does the amount of grain affect conversion? Does more mass/weight = higher conversion? Any input would be greatly appreciated.