I hit a cow elk in the heart with a 400 gr. muzzleloader bullet, and it ran 75 yards with no blood trail. X2 on Terminal Ballistics Research. That website is worth the read. They talk about the autonomic plexus, which is in front of the shoulder. I hit that on an aoudad and gemsbok, and DRT. After looking at the anatomy of elk, I try to aim just a little above center. With a lower velocity, or a muzzleloader, a scapula shot doesn't ruin as much meat. A .45 cal. 405 gr. high shot on or just below the spine will drop them in their tracks. I saw a low spine shot drop a cow, leaving a 4' half circle of blood spray from the lungs. I almost always hunt muzzleloader, so I go for the high percentage shot with the most room for error. I believe that to be on or just behind the shoulder, a little above center.