Update: I am the OP and am thankful for the positive responses. I used the same gun and bullet combo this year on my biggest whitetail to date and had good results. My gun loves the round and I like the idea of all copper bullets, so I needed to try it again. I anchored the whitetail at 326 yds, which is very near the maximum range I will shoot. The bullet entered behind the shoulder and exited through the front of the other and I was able to see the deer go down through the scope. I have never had my skills and patience tested so much for a clear shot. The wound channel wasn't ridiculous, but I can't argue with the results.
Unlike its antlers, the mule deer I shot last year had an enormous body. This coupled with possible/probable operator error may have resulted in the delayed kill, which was the subject of the original post. I may never know why that didn't quite go as planned. Thanks again to everyone having good input.