I've recently noticed that my mash efficiency plummets when I use a decent amount of wheat malt in my mash. To see if this was really the culprit, I went through the past couple of years worth of recipes and plotted out the amount of wheat malt used (in lbs and % of grist) vs. my mash efficiency for the recipe. I know correlation doesn't necessarily equal causation, but I'm going to go with causation in this case. I am assuming that given the smaller kernal size the wheat malt is not getting crushed very well at my LHBS. I wonder if having the wheat crushed separately would work better.