Ammunition and "Chargers"
As mentioned the K-31 is chambered in the 7.5 Swiss caliber (7.5 x 55). The ammo is referred to as GP-11 (Gewehr Patrone = rifle cartridge). The ammo is typically packaged in 10 round boxes with 6 boxes in a "battle pack". The bullet is a spire point boat tail design with a lead core, Cupro Nickel plated steel jacket. The diameter is .308. Many reloader who have a hard time finding brass cases resize .284 Winchester brass and use one of the many .308 diameter bullets available.
GP-11 ammo is NON-Corrosive!
The 7.5 Swiss is on the left shown with two other common (to the Cruffler) rounds, 8 x57 (8mm Mauser)and on the right, 7.62x54R, which is a Russian round.
Box - Contains 10 rounds
"Battle Pack" - 60 Rounds
The rifle can be loaded several ways. The 6 round magazine can be loaded manually and then inserted into the magazine well. The cartridges can also be loaded individually by pushing them in through the top of the reciever with the magazine already inserted in the rifle. Lastly the rifle can be loaded through the use of a "charger". The chargers are made of a wax-like coated cardboard with metal edges. It fit's into a groove at the rear of the reciever. You can then use your thumb to push the rounds into the magazine.
At this writing the Chargers can be purchased from Tennesse GunParts. Don't overpay for these things! I see them at gunshows for up to $4.00 a piece as well as the common online auction sites for about the same price. I bought 12 from TGP's for $20.00 delivered (.60 a piece). Buy a bunch as they are not built to last forever. Layne at Tennesse Gun Parts also carries many replacement parts for the K-31's.
