.243 and lots of practise (of course that is with ANY firearm). I just recently bought a New England Firearms .243 for my wife the day before thanksgiving. She has never shot a high-powered rifle before and had never really hunted except just sitting on the stand with me. Now she loves it! She has already taken a deer with the rifle.

She is small only 5 foot tall and about 98 pounds and the recoil does not bother her at all. I am impressed with the caliber and rifle.