I mashed 5lbs of 2-row at 148 for 60 minutes and looks like around 45% efficiency. Typically my BIAB with no sparge gets me 60%. The LHBS did the crushing, it seemed fine to me. The one thing out of the ordinary was that after the mash I let my friend do the rest with very detailed instructions and of course he misread and boiled for an hour without adding hops. So, I got him to do a 2nd boil with the hops. Obviously, this should not have affected SG. This batch was a partial boil that was topped off. So the efficiency is based off of the measured OG after the batch was at desired volume. Rather than do any math I just plugged in efficiencies into brew cipher until my OG came out. The volume was determined by sight. The target was 3.1 gallons and there is a 3 gallon marker so a little bit of guess work goes into it. Here are my ideas: 1) The LHBS crush wasn't enough. 2) My friend topped off with too much water. 3) My friend doesn't know how to correctly read a refractometer. 4) Sugar stuck to the sides of the pot during all the boiling? What do y'all think?
Shake it up, calibrate your refractometer, take another reading. Your efficiency could be that low, but with a very iffy refrac reading, there's no way of really knowing for sure what you've got.
