I'm shooting Easton Axis 300, 50 grains brass and 1.75 inch cut Thorn broadhead at around 272 fps. Shot an antelope very slightly quartering to me at 55. Heard a loud crack. Penetration looked horrible. Entrance was a large gash that appeared mid body behind the shoulder while standing, it did look like it was in the scapula when it was bedded. Exit hole was very tiny and high, blood trickled out, and eventually dried. Didn't recover the shaft or the antelope. I don't think I hit any vitals because I sat on the antelope for almost 7 hours waiting for him to expire. He ended up running off the unit after I failed to get another arrow in him. I'm open to all theories.