I've been using my system for over a year now, and have noticed that I almost always come out about 4 points below target on each brew. For instance, beersmith says the amber ale is 1.059, and I usually hit 1.054. Pretty consistently.
Here's my setup:
Igloo Ice Cube 15 gallon mash tun. Batch sparge (I stir it up and vorlauf again). I usually end up draining the mash tun at the end of the sparge to hit my boil volume.
Today, I even went with a longer boil (105 mins), and still only hit 1.052.
I suspect the LHBS doing a bad grind. But beyond that, is there something in my process I can look at?