I shot a big body 10 point whitetail at 500yds with a 16 inch 5.56 AR. Bullet was 68gr Hornady HPBT. Have it on video somewhere.
Buck was rubbing antlers on corn stalks and never reacted to being shot. Shot trace is easy to see on the video and the bullet penciled through the lungs.
A few more shots before the buck was down.
I now try and stay around 300yds max and use a bit better bullet for the task. The Hornady is fine if you have some speed but it has a low BC.
