Here's where you shoot at an elk regardless of what you are useing as a firearm. (SEE THE RED DOTS) Of course archery equipment would be different.
If you got the shoulder shot then shoot the shoulder. If you can shoot it behind the shoulder shoot it behind the shoulder. If you got a frontal shot like the one in back then take out the shoulder and heart. If you got a quartering away shot like the one in velvet then shoot through the liver, lungs and out near the offside shoulder.
All of these are good shots with a decent cartridge and the proper bullet.
