The Hornady 75gr was designed for the 1/9 twist barrels, but they do not work well in all of them. The reason is that not all are truly 1/9, some are closer to a 1/8.5, and some are closer to a 1/9.5, and then how tight they are. You just have to try them and see if your barrel will. Otherwise, go down to the 69gr BTHP and shoot away. You won't get as good of a score in the long run, but if you are starting out, they will probably out shoot you.
The 62gr SS109/M855 bullets are the length of a 69gr bullet, but are lighter due to the steel penetrator core. It is not the weight, but the bearing surface length that matters.
If you already good, or when you get there, put on a 1/8 or 1/7 twist barrel and move up to the 77 or 80gr VLD (not magazine length).