You probably hit ribwith your lung shot and had a deflection to the spine or central nervous system core. This happens quite often. My brothers, a cousin, and an uncle are nutjobs and will disect a deer until they find out the entry, theexit, and everything else in between. You'd be amazed if you saw how many times stuff like this happens. I've hit a deer with a perfect broadside shot with Nosler BT's at close range andit acted likeit wasn't even touched...due to no expansion time. Just a freak thing undercertain scenarios.
Certain guys love certain guns for whatever reasons. I hunted WI whitetails with nothing but .30-06's nearly 30 years before trying out a 7mm-08 just for Sh**s and Giggles. Love that gun too.