I have a 7prc built with a vespar medium, 3.4 mag length. Works awesome with factory ammo, Hornady bullets, and berger vld's.
If you're thinking berger 180 hybrids or 175 elites you may have to jump emm a bit for mag length. There isn't much left in the neck when seated to the lands with a saami reamer... which has a little too much freebore for those two bullets in my opinion.