Hodgdon data does not list Varget. Varget would seem to fast, and your load to hot. Different brands of brass can give high pressure with starting loads.(Prvi Partizan in 308win) H4350-44gr. w/ 168gr looks like a better/safe load. I do not own or have i ever owned a 7.5x55, so take it for what its worth.
Varget is definitely not a "hot" load in this rifle. The rounds I shot yesterday with "Varget" were not the ones showing case head separation, they were new GP-11 rounds. I used Hodgdon's .308 Winchester load data for developing loads for the Swiss 7.5 x 55 along with recommendations from many that have used this powder with good results. This round in a K-31 is very accurate and I really don't believe it is causing the case head separation (but I've been wrong before). Thanks for your input.
Best,
Chuck