an important thing to remember when hunting deer, whether whitetails or mulies in my opinion, is to keep your impact velocity relatively high with a bullet of proper construction to allow its jacket (out of a rifle, i mean) to open up and achieve a quicker kill. a bullet that is relatively heavy for caliber, like a 180 gr' projectile in a .308 cartridge, may not achieve that impact velocity as readily as a 150 or 165 gr' bullet.
(handgun projectiles are designed to open up, oftentimes, at relatively low velocities. that's the reason for the success of the hornady xtp's)
just my two cents,
ss'