Way back in the dark ages(pre-internet), I got my first K31. The only locally available 7.5x55mm was uber expensive Norma. Fortunately, the Shotgun News was full of distant dealers of the good stuff. Surplus GP11 was cheap and crazy accurate, but Berdan primed. At that time though, factory Portugese ball ammo was also cheap though under-powered. But it was Boxer primed! So yes, I grabbed a bunch of it. If my crystal ball was working, I would have got more.
Just a portion of my brass stash.
Fruits of my labors.
Three red stripes denote that upon firing, the expended brass will show that they are thrice fired.
Myopicvisionary 