I was deer hunting yesterday on a late-season 600-series Willamette unit tag. I have access to private property (a vineyard) on the condition that I use a shotgun. I am using a Remington 870 with a rifled barrel and sabot slugs that are accurate out to about 100 yards. I attempted a 50 yard head shot on a doe that was lying behind a small rise which hid the rest of its body. Its not a shot I would normally attempt with iron sights, but I figured I would either miss cleanly or kill immediately. I pulled the trigger, and the deer flipped over on its back, kicking its legs in the air as deer often do after being shot. It then laid motionless. I assumed that I had made a direct hit. As I approached the deer.....it got up and ran away, displaying no sign of injury. I could see it bounding away thru the vineyard, it wasnt limping or hunched over as if gutshot. I found no blood or hair anywhere. I followed it around the vineyard for over an hour, unable to get within range for another shot, and it was apparent that the deer had not been hit by a 524 grain slug moving at 1200fps. It even resumed feeding after awhile. I was glad that I had missed cleanly and not wounded the animal, but I am at a loss to understand why it flipped on its back and acted dead. Is it possible that the slug made some sort of "shock wave" in the air that stunned the deer? There is no conceivable way that the deer could have survived a head shot from a slug at 50 yards. Opinions?