A few weeks ago a friend of mine went out West with a .338 and collected both a nice elk and a mule deer, and while the elk succumbed without a struggle, the muley made a point with his passing. The critter was shot in the shoulder, downhill, at 265 yards with a 225-grain Barnes TSX bullet at 2,750 fps. I know all this because I loaded the ammo myself.
Rather than dropping like a stone because his shoulder was smashed and his innards were pureed, as indeed they were, the mule deer did his level best to get away and required three more shots to convince him that it was time to call it quits.
None of this is detracts from the .338, or the Barnes TSX, or the shoulder shot. Almost always, when a critter is struck there and the bullet does its job, the beast goes down right away or within a few steps. The shoulder shot is the way to go if you have a bullet that will break bone reliably and if you are shooting something big that may object to the proceedings.
The lesson you can take from this incident is that shot placement is an inexact science; it’s a matter of going with the percentages. There are no guarantees handed out. Whenever you shoot, always be ready with an immediate second shot. Or a third. Sometimes, no matter how hard you hit them, they just don’t cooperate.