This is probably because there is no real market for a 175gr partition load since the 160gr partition is plenty of bullet for game including moose and elk.I
Ditto..... There is really no practical need for a 175 grain load in the 7mm Rem mag. 160 grains is more than enough bellet for anything that you would use a 7mm mag for.
Federal does load the 175 grain TBBC but it's hard to find. Winchester loads a 175 grain power point.