I have been using American Wood Fibers pellets for the first part of this winter. I have noticed that when putting in three bags , 120 lbs , they all fit in my hopper and I can close the lid. I have run out of them ,and am now using Agway brand[ Hammer Hot Ones So say the owner of store] and 3 bags lbs fills the hopper heaping over , and can not close the lid. So is 40 lbs really 40 lbs every where ?