So the deer ran 40 yards. What's the problem?
If you want the deer to drop in their tracks then either shoot them in the spine or through the high shoulder. If you don't want to do this then expect the deer to run off a short distance.
I guess we can thank the hunting shows for the general hunting public expecting that their bullets should be some kind of magical lightning strike where the animal just gives up the ghost right there. The fact is most animals run a short distance.