Depends
If they are close with open sights, I would try a head shot. Close is under 50 yards. Farther out I aim behind the shoulder. Most of my rifles shoot above the front blade so I hold six-oclock.
I've killed deer with Krag, 1903A3, Garand, Jap T44, Swede M38, Arg 1909 Carbine, Arg...