I like what Denny says, we're not brewing gaps. Not totally sure what it means but I've found that mill gap depends on your system. I was milling at about .030 and was getting a harsh tannin thing. Efficiency was about 72%. Then I opened it up to who knows what, but my hulls are intact and the grain looks to be about 5 or 6 chunks per kernel. Tannin thing gone and my efficiency went up. Go figure