Gosh, for a first time hunter you cannot go wrong with a 30-30. You can pick up a nice used one for very reasonable, the shells are cheap to practice with until you get good with it. I just cannot see a first timer trying to take a 300 yard shot with any amount of confidence no matter what caliber you give him/her. A .243 would be my next choice. And if the kid is experienced enough or big enough then a .270 would last them a lifetime. A .243 will too for deer hunting but if they decide down the road to hunt for larger game then a .243 just doesnt have the poop for that.