Oooooooh... Hmm.
For all round use in today's world, I would take k31.
For hunting I would take the swede mauser.
For only gun I would ever own, but have access to maintenance, k31
For only gun I would ever own, but essentially use it until it breaks, Swede mauser.
Overall I would saw K31, however pre-k31 I would take swedish guns.
My reasoning:
k31 action is just slick. Strait pull, amazingly thought out design that can shoot like no other milsurp I've found. It's heavy though, due to complex design and heavy building. The 7.5x55 is neat, but doesn't really excite me like the 6.5x55. It's certainly accurate, but many cartridges are. Earlier swiss models are not as good, due to mechanical insufficiencies in my eyes.
The swede mauser in my eyes is in many ways equal to the K31. Typically very accurate (or were when new), well made, and chambered in 6.5x55. The swedish guns definitely are revolutionary in that they're one of the earliest and best bolt action designs in existance, and it took almost 40 years for the K31 to surpass them. The gun itself must have been far cheaper and less complicated to make than the K31, which would have helped arming a nation when bottle necks are to be avoided at all costs. However, on an individual level, they're simply a design that was 40 years older. To counteract that is the fact that they're chambered in 6.5x55, which is one of my favourite cartridges. Almost no recoil and super flat shooting really get my support. Of course, bullet weight tops out lower than the 7.5x55.... but I can live with that.
In the end, I own a swedish sporter in 6.5x55 and a k31 for fun
