It's not uncommon at all to have deer run off after being hit very good even with large extremely hard hitting calibers. I've killed more deer than I could possibly count over the years, and yes, a shotgun with buckshot sometimes seems to knock'em off their feet. Other times though, I've had'em run off like they weren't hit after taking mutiple pellets through the vitals.
It's the disruption of blood supply to the brain, or nervous system that ultimately puts animals on the ground. I believe that when deer drop in their tracks from a bullet through the heart/lungs it's usually a situation where the deer was completely at ease, and was taken completely by surprize.
I think I might have posted this before on these forums, but I once killed a young buck with a 30-06. I can't rember the load, but at that time I was using mostly 150g SP's, and 180 RN bullets at maximum velocities in that rifle. I'm thinking that day I loaded up with the 150g SP's(best I can remember)
That little deer was a fairly close shot, and I hit him hard right dead through the heart/lungs. He took off, and I swear, he acted like I'd clean out missed him. I watched him trot, not run several hundred yards out of sight, and firmly believed I'd just messed up, and pulled the shot. I went on to the house, and pretty much accepted that I missed an easy shot, then suffered through a couple hours of the other guys ragging me for being such a poor excuse for a hunter. You know the drill! LOL!
After absorbing countless attacks to my pride, my uncle came in, and said there was a deer laying out the road in the feild. He said it was a small buck, and looked fresh. We piled in the truck, and went to see it. It was my deer, and had gone at least a quarter mile before falling. I'd hit him perfectly behind the shoulder(quartering away), and the bullet exited the off shoulder. The lungs were devestated, and the heart literally looked like a bomb blew it up. It still amazes me that he ran as far as he did, with no vitals at all.
