RE: purchased youth Elk rifle
I don’t know about the 180 grainers. I think I would stay with the 150's. Flatter trajectory and a little less recoil. The .308 doesn’t usually like anything above 165's. Or at least that’s what my experiences with them has been. The 165 grTSX would do a great job on a cow elk! Federal offers them in a "Premium" load. They still hold 1000 ft/lbs at 500 yds. Not saying you would shoot that far. The ballistics chart show if you sight dead on at 100 yds, you will only have about 4" of drop at 200. Plus the TSX is a great bullet for weight retention! 98-99% in most loads!
Another great choice would be PMC'c loaded with a 168 gr XLC. PMC is nearly hand loaded quality. Before I started hand loading, it was all that I would shoot. They group very well and use premium bullets, like Barnes.
Let us know how your kids hunt works out. Love to see youngster getting out and enjoying the sport!