I carried a .243 as well on my first hunt, and have used every one of those factory 100 gr. loadings from Remington, Federal, and Winchester to take deer and antelope. I probably used more Remingtons and Federals, simply because that's what the stores I could afford carried.
My recommendation is to take a box of each to the range and see which shoots the best in her rifle (by "best", I mean which one shoots the tightest groups).
I haven't had a single problem with any of those bullets as long as I did my part getting it where it needed to go.
Just about any 100gr bullet for the 243 will do fine on deer, as long as it was designed for hunting. From cheap blue-box federal ammo and Core-Lokt PSPs, to Nosler Partitions and maybe even Barnes bullets (I don't know if anybody factory loads barnes for the 243 @ 100gr?) they will all git 'er done. I'm not sure where you are from, but if you're hunting some of those skinny southern deer, as light as 85gr bullets will also do the job. They open easier than the 100gr bullets and that's more desirable in smalleranimals than in 300lb saskatchewan whitetails To start, I suggest you get at least 2 different kinds of bullets and see which one groups better. Most of all, make it fun for your daughter. Bring along a 22 to the range maybe to do some plinking between groups, some shoot n see targets might also make it more fun.
Location: S.W. Pa.-- Heart in North Central Pa. mountains-
Can't really add anymore than what's already been said..............you will just have to try various brands and find out what one(s) your particular gun likes best. Some serious handloading should really give you the proper combination, if you are so equipped and inclined.
My son and I both use Remington 100 gr. PSP Core-Lokts in our .243s for deer hunting, and we've gotten great performance. He's got a Model 7-Youth, and I shoot a Model 700ADL. If you hit the vitals, they work great! As stated before, pick whichever of the listed cartridges shoots best in your rifle.
IF YOU HAND LOAD LOOK AT THE BARNES X BULLET, 95GR AND A LOAD OF VARGET TO WHATEVER SHOOTS BEST IN THE RIFLE.
IF BUYING FACTORY TRY THE MAJOR MANUFACTURES TILL YOU FIND WHAT WORKS BEST, FED REM AND WIN HAVE ALL PERFORMED WELL IN MY RIFLES.
BEST OF LUCK