Bobcat, I used to hunt with a 6mm, which is the same sized bullet as the .243. I once shot a 5 point in the shoulder at about the same distance as you, and it didn' t put him down. The bullet lanced off his shoulder but lucky for me, it bounced off and took enough of his heart that it killed him relatively quickly. I learned that if you shoot them a little further back and get a good lung shot with the 6mm (.243) they' ll run further but you' ll find them within 100 yards.
Sorry to hear you that you lost him. It happens, unfortunately...