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
Agreed - I have encountered stuck sparges at too tight of a mill setting, as well as it becoming too hard to mill for my cordless drill (or hand crank for that matter). I backed it off to about .035-.040 (guessing by eyeball) or so and like my crush. Like I said, I have it marked so I can be consistent. I am not terribly concerned about efficiency, but I don't want terrible efficiency, either (72-75% is fine for me).