Most published C.O.L. loading data for the 7.5x55 Swiss comes from the M1911 and M96/11 Swiss rifles which have a longer throat than the K31.
Only Vihtavuori and Norma list the proper C.O.L for the K31 with their bullets.
They refer to the cartridge as GP31 to differentiated it from the GP11 round as used in the longer throat from the older generation rifles. Still same cartridge and specs.
If I may, I'll post some links about the topic.
Posts and Chart for Commonly used bullets and their C.O.L in their K31s