I love this place. I think we have been ignoring the most important advice for this young hunter. Make sure the rifle fits her! A young person trying to shoot an adult length stock is a recipe for a poor shooting experience all the way around. One thing I have been doing is going through stuff in my disabled state, and I found the stock I started my son on when he was 12. I had to laugh because he is now a 6 foot 5 inch adult! Length of pull on that stock is 12 inches. Along with Farleg's advice on practice, make sure she it practicing good form. Work on building her confidence. Make shooting fun!
In my opinion, the recoil difference between the 112 and the 124 isn't significant. So pick a bullet that gives you confidence. That is why I have settled on the 118HHT. Besides I like being a little different. I'll hunt elk with that bullet if I have to. With my broken neck, I might have to hunt with a light recoiling gun this year. Besides the nice compromise, I have confidence in the round. Last year I hunted with the 115 grain Power Hammer. The nice thing about reloading is developing your own load. Have your daughter participate in developing her own load. The number one round for moose in Scandinavia in the 6.5 Creedmoor is the S&B 120 grain all copper bullet at 2,840 fps. A 112 or 118 or 124 Hammer properly placed should work well on a cow elk at a reasonable distance.
Here is my favorite 6.5 Creedmoor load.
CALIBER: .______________6.5 Creedmoor
BULLET:________________118 gr. HHT
POWDER:______________ 45.5 Grains of StaBall 6.5
PRIMER: _______________CCI-BR2
BRASS _________________Lapua once fired
COAL: _________________2.780" 1/4 Lee crimp
BARREL LENGTH: ______24"
TWIST: ________________ 1-8
VELOCITY: 3024 fps
RIFLE: Tikka T3 Lite
Temp 48F
Elevation 2500 ft
Excess pressure signs at 46.2 gr.
Accuracy node was at 45.5 gr. 3/8" 5 shot group at 100 yards