As stated above the bolt thing is a pain especially with the 7.62x39, PPC type cases...
I started my kiddos on a TC contender in a 300 blackout..suppressed, good trigger, single shot...accurate. I put a M-4 style adjustable buttstock a really easy shooting adjustable set up...and with a 130 grain Barnes...deadly out to 150..our max range to start out...
As they grew, I bought my daughter a Savage lady hunter, in 6.5 creedmoor...she is 12..big for her age but shoots it well...we also have a short action 6.5 creedmoor on a manners CS..my wife and both kids like to shoot it too..especially off a Tirpod with a pigsaddle on it...
I'd suggest A encore/contender...or aAR in a Grendel...adjustable--easy and fun to shoot...