Lots of good calibers out there to choose from. I purchased my daughter a Rem 700 youth in .243 when she was 10yrs old and she used it a couple years with no issues and harvested several deer with it. At age 12 i bought her a Rem model 7 .260 and she used it for several years before going to a full size 700 in .260 and she's still using it at age 20. If i had to do it again i would have got the .260 to begin with, it has a very mild recoil and is no doubt pure deer poison. Others to consider would be the already mentioned 25.06, .308, 7mm.08, and the 6.5 Creed, all great calibers and imo you wouldn't go wrong with either. Mike