Yeah,I do pb/pm biab in my 5G ss BK/MT. The more volume of grains/water I have,the better the heat retention while wrapped up during the mash. Typically,1.5 QTS water per pound of grain works well. Then sparge up to my boil volume. For me,2G of local spring water to 5-6lbs of grain,sparge with 1.5-1.75 gallons of the same water for boil volume of 3.5-3.75 gallons in said 5G kettle.