Reduced recoil loads are the ticket if she is recoil sensitive.
Some kids are and some are not, my youngest son prefers to shot my 280AI with no brake over his 6.5cm with reduced recoil rounds. The Ackley IMO kicks more but it is very different from the lightweight 6.5cm. My oldest prefers his 6.5cm with full loads and 142gr bullets which kicks more than my Ackley.
Really it just comes down to what you want her to shoot. A .243 will kill elk just fine, I wouldn't hesitate to hunt elk with one and have killed more elk with a .243 than any other gun I own. I have other rifles I built and chose to take those instead of the .243 nowadays. The 6.5cm is a cool round and that's what I purchased my kids because they have great ballistics and I reload and like to tinker with loads.
If my only rifle was a .243, I wouldn't think twice about hunting any animal with one. I personally like unique cartridges, Ackleys, 280 Remington, 260 Remington, and anything Ackley improved is even better.
Any cartridge designed around the 308 or 30-06 parent case is going to be a great all-around cartridge for anything we hunt in the US.
If you don't reload your choices are limited for reduced recoil rounds unless you have a buddy to reload for you. Hornady offers reduced recoil load for the, .243, .270, 7mm-08, .308 and 30-06. HSM makes them for the same as well as 6.5 cm, 7mm & 300win.
I agree with the above, trigger time is the key and having something they enjoy shooting and want to go shot will help get them better, if a kid is afraid of a gun they won't want to shoot it. With the reduced recoil loads my kids would shoot as much ammo as I would let them shoot.
Here’s a picture of my 50lb, 9yr old at the time, shooting his Kimber Hunter.
