Elk are big, tough animals and need to be hit very hard by the arrow to kill them. The most lethal shot is a double lung hit, but they can go long distances with hits through only one lung.
The best shot for a bowhunter is an elk standing broadside. This angle is ideal for a double lung shot, as it requires the least amount of penetration to reach vital organs and causes them to collapse.
Pick a spot on an elk standing broadside about 4 to 8 inches up the front leg (directly behind the shoulder) and another 6 - 10" up from that point on the rump. This is where the lungs overlap the heart and are protected by large shoulder bones.
A bowhunter can also target the lungs with an arrow, but it's harder to penetrate those larger areas and a single lung hit is less lethal.
The quartering-away position offers many lethal targets for firearms and a good aiming point for a bowhunter is directly behind the shoulder, a few inches back from the head of the animal. This area is covered by heavy shoulder bones, which shield the lungs and intestines from penetration by the arrow.
If you're hunting slow-moving elk, you can take a moving shot if you're well prepared and you have good visibility. However, only move your arrow when the bull is close to you and when you're sure that you can shoot without moving your stand.