I agree with JagMagMan. .243 would be the minimum I'd hunt whitetail deer with. Even that is a bit on the light side. I would say .270, .30 cal, 7mm mag. For type of hunting in N. MN where I sometimes hunt .30-06 is a good all around choice, if shots are 150 yds or less as they ar 98% there. They have many choices of not only slug weights and types to suit most any situation within those limits. A .30 caliber 06 or .300 WM will do considerably more internal damage and have a greater shock affect on a deer than a lesser caliber like .223 you mention.

That's my opinion.