Accuracy is more important than the caliber size. My 8 year old grandson took his 1st deer the other day with a perfect lung shot & the deer went 19 yards with a good blood trail and lots of internal bleeding. The rifle was a Thomson Contender .223 caliber shooting a 61 grain soft point. We have practiced and practiced with not only paper targets, water bottles to show the explosive force of a bullet as well as deer targets. He had to prove he could make the shot every time he shot at a target. After he shot the deer I asked him where he shot it and he told me and when we examined the buck he hit exactly where he should have and where he told me he had aimed.