They are actually .308. bullets. I have been surfing the Swiss websites for several weeks and have learned a bunch. One site even has the manual translated to English for download. Try the Swiss forum on gunboards and these sites for more info.
http://swissriflewebsite.com/
http://pub18.ezboard.com/btheswissri...ommessageboard
Lots of reloading info on these sites and friendly folks. Another neat thing about the K-31 is many have tags under the butt plate with the soldiers name and info on it. many folks have actually got in touch with the soldiers who were issued the rifles.