A thirty caliber cartridge would be good. A 30-06,300wsm,300win,300wby.Heck.......you could even take a 280 ,but it would be better to take one of the 30cals I listed.I think many people make the mistake of giving young people light compact rifles.If the person is really too small to use a standard sized rifle ,then fine,go for it.After all,fit is important.But just remember that the lighter the rifle,the more kick.A 5lb 30-06 kicks much more than a 8lb 30-06 with the exact same load.