Eric,I have noticed something similar to what you experienced. I cook on a Backwoods PIglet and Fatboy. When I use IBP butts, either from Sams or my food service company, I can damn near count on them being done in 12 hours. I cook at 225* and the butss weigh 7-8 pounds. When I buy the individually wrapped butts of the same size from a local grocer, it may take 20+ hours for the bone to pull. My assumption is this: the butts have been frozen and thawed more than once. Only an assumption. Odis