Knight 50cal. using 5o grain of 777 pushing a Barnes Spitfire 245, deadly deadly deadly. I only let them shoot 50 gr on account I dont wont them to develop the dreaded flinch do to a heavier recoil. We use shooting sticks so they can support the weight of the gun and my oldest has killed 3 deer with this setup 2 does and 1 nice ten pointer. The oldest is now 9 and the #2 son is going this year, he is 7. My words of advice is start off with small loads with younger kids and keep the shots close to build confidence in themselves. To big of a gun with a heavy load will discourage most kids from hunting or shooting, Hell it even discourages a lot of adults.