I found a Ruger compact in 308 that I am thinking about for my 8 year old daughter.To what extent can the 308 be loaded down?

I am just collecting reloading equipment so have no clue yet.I have read about reduced loads with cast bullets.What other standard rifle caliber would reduced 308 feel like?

Shots would be limited to under 100 yards to start her out so not too much worry about down range ability.

My original thought was 223 or 243 but I ran up on this Compact Ruger.I like the idea of a rifle she can grow into but not if initial recoil can't be delt with.