Mines kinda similar to yours Dave. I saw a Bedded Buck in the Grape Rows behind our House, he was looking in My direction, I think he was asleep. I aimed the 50cal Dixie Gun Works ML loaded with a Round ball and 90gr's of 3F at his lungs from 77 yds and fired, he never moved, hs head just went down.
When I came upon him I saw the shot was a tad high in the lungs (it's tough to judge a bedded Deer's vitals) Anyway when I rolled him over there was no exit hole. When I field dressed him I still could'nt find the Ball. Later when I cut him up I just had to find it, I was puzzled.
Come to find out the ball glanced off the ribs, hit the spine and travled the spine into the Bucks head into his brain. I had to cut off the top of the scull plate to find it.
(BP)