I have shot a few deer with my Whelen, two were a couple of the longest tracking jobs I've had to do, but I was hunting elk at the same time and was using stoutly constructed bullets. The Speer Grand slam 250 grain works extremely well on elk and moose but is too hard to expand well on deer. On one buck, the Sierra 225 BT didn't expand, a lung shot buck ran over 100 yards, bullet didn't appear to open at all. I think most 200 grain bullets or a 250 RN would be fine for any deer hunting. But, NO more likely to put them down in their tracks than a normal deer caliber like .308. 7x57, .270 or 30-06 though. So, learn how to track. It's an important part of being a competent hunter.