It's usually about 3# per turn for most bows. Assume for the sake of arguement that your bow is 71# maxed. Take two turns off the limbs and you should be at 65#, give or take a pound.

Some guys think it variesd due to thread differences in the limb bolts, but this is not true. All 3/8" limb bolts have the same thread pattern. There can be some differences in limb construction or design, but 3# is pretty common.