I have tried a few of Jamil's recipes and have been off around 20 points on my OG. I think the concentration of my wort is off when I rack it to the fermenter. Many people here are saying cut the recipe in half from a 6 gallon to a 3 gallon. If you start with 7 gallons for the pre-boil on the full boil recipe, shouldn't the starting volume of the partial boil be 3.5 gallons. Also, depending on the evaporation rate wouldn't the pre-diluted wort be of varying concentration. So if my stovetop is boiling 1.2 gallons per hour vs. the book's 1 gallon per hour wouldn't my 2.5 gallons of concentrate solution be 20 percent higher than the book's affecting the OG of my wort once I dilute to the 5.5 gallon mark on my fermenter. Thanks in advance for any help.