I have had lots of bang flops over the years. All were either spine, neck, or head shots. Never had a double-lung animal go very far. This year, though, I did something I have never done. I shot a cow moose 3 times. I fired from 250yds on a broadside target. Seemed like it had no effect, cow just turned 180 and started walking toward the woods. As she approached the wood line, I was starting to panic, THOSE WOODS WERE THICK AND FILLED WITH DEADFALL, so from 275 yds I put one through her shoulder (she was turned a bit). She came up pawing the air and then laid right down. She probably would have stayed there if her brother would have left her alone. He actually got her up! Then I was desperate, I ran up as she took a step into the woods and stopped about 150' from her. All I had was a Texas Heart Shot presenting and she didn't want to move anymore. I yelled at her, she looked back toward me and I poked one right between her eyes. Gutting and skinning...first shot destroyed her heart. Second shot hit heavy shoulder bone and took out the shoulder, both sides if the ribs, and came to rest under the hide just missing the other shoulder. Of course, the head shot was pretty evident.
Bang flops exist, but circumstances have to be right. One doe I shot this year was 60yds off, walking slowly along a trail. I waited until she walked out into the spot I picked, then I threw a 165gr bullet from my 30-06 through her lungs. I have never seen a deer react that way. She jumped straight up into the air from all fours, kicked out while in the air, and then crumpled to the ground, dead. Her lungs were absolute jelly, but I could not find any sign of CNS damage.