Bagboy

As mentioned by Daryl, the 6.5x68 is an excellent high speed flat trajectory calibre that is mostly used in Europe for mountain hunting.

RWS are part of the RUAG Ammotec Group, which has a registered office in the US in Florida:
RUAG Ammotec USA Inc.
5402 East Diana St.
FL 33610 Tampa
United States
Phone +1 (813) 626-0077
Fax +1 (813) 626-0078
You may contact them for finding a dealer.

You may also check on their corporate website https://rws-munition.de/en for specific ballistic data about their 6.5x68 factory ammunition.

Last, a Mannlicher-Schoenauer 1958 NO model in 6x5x68 (5-round magazine) was recently sold in France by gunsmith Joel Dorleac, of which some valuable data and photos are still available at http://www.dorleac-dorleac.com/arme/mod-no-magnum/ (the link I provided might be in French, but information is also available in English on Joel's website).

Louis