6:55 AM opening day first Antelope we saw was so far away that it was hard to see with your unaided eyes. So we kind of drove up parrallel to it. I found it with my scope on 12 power and turned it up to 20 power to shoot
long shot near classic broad side. The buck was walking away and sometimes turning sideways to me. I was sitting with my rifle bipods down. Nearly level ground. It smashed a major rib on entry side is why the hole is so big. The bullet hit and shattered rib on the far side. We retrieved the bullet when skinning it. Bone or shrapnel put a small hole on the far side. That is the blood on the ground which sprayed out of the exit wound 20 feet. After the shot it kind of stepped forward and low arched its back and fell over without a kick.
My rifle is a 243. Time of flight to 400 yards is .40seconds. So at its walking speed I rough figured about 12 inches in .40 seconds and bullet drop of about 12 additional inches with my rifle zeroed in at 250 yards. The bullet hit right about where I wanted it to with my lead and added elevation. Since he was moving I didn't have time to dope in the scope and it was not major corrections anyway.
I used a 243 100 gr spbt at 3200 fps using .430 BC numbers The recovered bullet retained 83 grains and it is a 1/3 as long as it started out as.