i have a 9 year old son who hunted this past year with a 30-30. i want to increase his distance and will eventually put him with a .270. his sister is 7 and i want to buy a gun for her that she will be able to use for life - but let my son hunt with it until she gets older. what would be the best gun for my daughter for life that my son could use now? i was leaning toward a .260 or 7mm-08. will she need a 20" barrel? what model(s) is recommended? scope size and preference? thanks!