In my opinion, I believe the .243 Winchester is the best round for hunting deer, Black tail and White tail. I have hunted black tail for many years and I believe that the .243 is the smallest round to take down a deer. The smaller the caliber the smaller the entry and exit wound. That means less meat that has a bullet in it(more meat in your freezer). As long as you have a good shot, a .243 is more than enough to take down a full size buck. You can go larger than a .243 such as a .270, 30-06, or a 30-30. If you do go bigger in caliber size than that will mean a bigger entry and exit spot. Which means more meat will be ruined by the bullet. That is why I choose a .243 to hunt deer.