You will want to use the heavyest bullet that you can in this cal. My Speer reloading book lists the 70 grain has the heavyest, I really don't know if this will work for white tail deer, I am used to hunting with 30 cals that shoot bullets in the 150-165 range and they work well. This year I am going to hunt with a 243 useing 90-100 grain bullets. I posted a question on this web site a couple of weeks ago asking if the 243 was enough gun for white tail deer and 90% thought it was more than enough gun but I am not sure about the .223 The most important part is shot placement, the .223 has been legal for big game in several western states so if you can shoot it well than why not give it a try?