I do have another theory about that second shot, in light of some others saying the bullet is not well constructed. You very well may have hit just above or below the joint on the shoulder leg juncture. This bone structure is very strong and can cause a bullet to frag and blow out bone with out giving the penetration nessary to make it to the boiler room and shut down the ship. I have seen this happen!
I know I have had one true fail that I know of. 100gr core loct, 243, 450 yards. The deer shot bolt up right and dropped back into the woods. I waited about 30 mins before going to check out the hit. There was a solid blood trail and I thought,"he is dead at the bottom of the hill". One step into the woods and he jumps up and takes off up the next hill. Where he was lying was a huge pool of blood and I knew all I had to do was just wait a few hours and go get him. Then just over the a shot rang out! I followed the blood to the deer where a young man from next door had taken him!
He shot him from about 75 yards with a 280 and the bullet holes where with in 2 inches of each other! Nice deer for a nice young man! Next year I was using the 260!