The issue is that getting multiple family members shooting proficiently requires significant ammo down range. At $1.50/round, that money adds up.6mm ARC in either an AR15 or a bolt gun. Very mild recoil but enough bullet and energy to get the job done. I rebarreled my 6.5 Gendel AR with a Satern 6mm ARC 20" and I love it. It is very accurate and really fun to shoot. Ammo is running me $28 to $34 per 20. Can't recommend it enough for your purpose.
223 ammo can be had for one-third the price. It’s why so many of use it for a trainer.
For perspective, by 750 rounds, the cost difference of ammo could buy new stainless Tikka.