The K31 I shoot most originally did not like 168gr match bullets. All it really seemed to like were Remington 165gr SPCL bulk softpoints, and slower powders in the 4831 range. It came to me with a rather new barrel, and after being shot a lot, its tastes have changed.
Sierra has an accuracy load suggestion, and I substituted the very similar Nosler bullet: 168 Nosler & 43.9gr IMR4064. I used it in the Vintage Military match at Camp Perry this year with an RWS primer & Prvi case. It shoots better than anything else I've tried, but it is very temperature sensitive. In the spring, when it was cool, it would print a really tight group at 200 yards in the bottom of the 9 ring. In the 90F heat of August in Ohio, it put a nice group in the 10 ring.
Start low and work up. As I gradually increased the load, the groups were merely ok, but when I reached the charge Sierra recommended, the groups shrank.