the butt plate looks like it was drug out the rear of a truck, worn and rough,
That's typical of these guns rock. Like Jh says they were used! That roughness in the stock is commonly refered to as "snow burn". Others commonly call it "beaver chewed". But, think of it this way, these guns performed honest service and show honest wear. They WILL shoot! :grin:
As for replaceing them, I thought about it with mine too but decided that they would simply gon on with their lives as I got them and they have even picked up a few more character marks along the way.
Mine have been elk and hog hunting and have performed 100%.
Somewhere on one of the Swiss rifle forums is a translated field manual for the K31. Don't remember the site, but I have it in PDF and would be happy to email it to you.
Have you looked
under the butt plates yet?