cmdio: Congrats on your K31. You won't regret it. The reason the butt stocks on most K31s are chewed up, I believe, is from carrying them in the M1944 rucksack, which neatly positions the rifle straight up and down the spine, cradled inside the ruck, with the butt sticking out the bottom, where it can get royally banged up. This kind of carry enables troopers to scramble up steep rock sections with both hands free.
As for the clamp on mount by SP Products, its a jewel. It is so precise the clamp works like a QD mount with exact return to zero. The problem is, it sets the scope off to the right by about 3/4", great for a leftie like me, but normal people should get the drill and tap mount from the same outfit, is a better choice, since it positions the scope 3/4" to the left of bore center.
One more outstanding feature of the K31 rifle most people overlook is its suitability for bayonet fighting. That forward grip is just right, what can I say. All pre-WWII infantry rifles (not carbines) were designed for bayonet fighting as a back up. Modern design rifles compromise this feature, but still mount little bayonets. When the chips are down, its better than nothing. None of the infantry rifles I have ever handled come as close to ergonomic perfection for the bayonet fighter as the K31. I wish I had one of the 11" bayonets that fit the K31, until then, my rifle is incomplete. Someday. - CW