If you mean Elk, not big deer, but the real deal Elk. I shot my first one at 16 with a 30-06 and a 220 grain Silver Tip. I think with a young boy a good stock fit will be most important. If you know women hunters try to barrow one. I strongly disagree with anyone that say the 243 is a good choice for elk, sure it will kill one, but that does not mean it is well suited for giving good kill power on Elk. I good Nosler partition 140 grain 260 Rem is about the smallest I would go. I have one, but I would say it takes an experienced hunter to use it well for Elk. I would put a young boy on a 30-06 stocked to fit him.