gjszabo,
Sorry I can't help. I have loaded the 180 TSX but not the 168 grainer. I was able to get the 180 grains of triple shock using 99.0 grains of Retumbo at 3480 f/s; pretty hot but no sticky bolts, or leaking primers... did get loose primer pocket holes. I say you should safely be able to get 3400 f/s with the 168 grainer. Has to be everything you need in North America. Be safe!