goschman, my efficiency varied too depending where I bought the crushed grain. Owner of a LHBS let me mic his mill, turned out to be .055. It prevents stuck sparges but kills efficiency.

Instead of brewing to see where your efficiency is, see if the LHBS will let you mic their mill. If you have a couple of LHBS to choose from pick the one with the smallest setting, assuming it is not too narrow to give a stuck sparge.