The .45/70 destroys less meat than even a .243 - I know, having used both. A .45/70 with proper hard cast flatnoses just punches a .45 caliber hole through the target.
You standard high velocity rifle can take out an entire shoulder on the offside.
I would think that a .45/70 would be the perfect deer rifle in thick cover like Georgia. It isn't overkill at all, in thick cover like you have, it could argued that the more typical rifles are "overkill".
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Keith
The Bears and Bear Maulings Page:
members.xoom.com/keithrogan