This was many moons ago. Late season ML. My friend and I hunt the thickest nastiest stuff in our area. Full of black birch and scrub oak all tied together with good old greenbrier. One of us usually tries to find an area with some visibility and the other does a slow walk through toward him (as if you could walk fast).
Anyway, this one time I was the lucky guy on stand and my buddy pushed 3 deer to me. I could catch a glimpse of them every once in a while as they eased out in front of him. The first two managed to get past me. But the third one took an alternate route and was walking directly away from me, tail up, about 40 yds.
With my Hawken flinter loaded with a 275 gr Maxihunter and 100 gr of Goex FFFg I shouldered the her and pulled the set trigger. Settled the front bead just below the base of the tail and touch her off. Throught the smoke I could hear some trashing then silence. I had thought I had missed her and she was running off. Then I saw her white belly. I reloaded and walked up only to find her stone dead. It was obvious that I had hit her but I could not find an entry hole - at least until I started to dress her out. (my friend was teasing me and said I gave her a heart attack).
During the field dressing we came to find out that the bullet entered the rectum perfectly and did not break any skin. But the insides were, to say the least, a total mess. I never did find the bullet but it sure did a bunch of damage right up into the chest cavity.