A .243, especially with a moderate load and traditional cup and core bullet can be handled by most 10 year olds. If hunting from a blind, a heavier rifle would reduce recoil even more. Avoid a muzzle brake and make them wear ear protection every time they shoot- even if suppressed. Recoil and...
.they are tough, but can’t live very long without their lungs. Shoot a good bullet accurately….any reasonable long range caliber that YOU can shoot will work.
I started out with a .270 Win. I then had to experiment killing deer with every other cartridge I could try- only to realize the .270 really is as good as it gets on deer!