I have no idea what the gap on my mill is set to, and I don't really care. Learn what a good crush looks like and how it acts in the mash tun, and settings won't matter to you. Not to mention, a setting that works with one person's system might not work for another's. Keep in mind that you're making grist, not gaps! The finer you mill your grain, the higher your efficiency will be. I advise you to keep reducing the gap slightly every time you brew. If you have runoff problems open it back up a bit next time. Take a good look at your grist at that point and you'll know what you;re looking for from then on.