In the days of the PE 57 in the old 7,5 caliber, they were required to keep a sealed can of Gewehrpatrone 11 (G11) ammo- the cardboard boxes are of 10 rounds [in a convenient six-pack carton], the military tins of 24, as I recall, the PE57 rifle having a 24 round magazine. The older straight-pull rifles had a 6-round magazine, and when I shot in a Swiss rifle match at Thun, there were about a quarter of the shooters using the older rifles, mostly the m/31 straightpull carbine. I had a rebarreled German Kar 98k, which several of the Swiss admired, and remarked that it was a shame that I'd be unable to shoot it that day, as they had none of the 7,92x57mm German ammo. Which was when I happily pointed out that it was rebarreled, and that I had reworked it with a .30 Browning machinegun barrel with a .308 bore diameter, chambered for, you guessed it, the Swiss 7.5 G11 cartridge. I did pretty well- I was a LOT younger then- but a LOT of the Swiss shooters did much better, having the *home court* advantage and several years of familiarity with their chosen tools.
As I recall, the cost for ammo at the match was about $0.04 per round. I took about 600 rounds back to Germany with me, things being a lot easier in those days. Oh, btw: those who reload 7.5 Swiss can use American .308 diameter projectiles meant for .30-06/.308 ammo, including tracer and AP. Which was one of the reasons I reworked my K98 to that caliber.
I don't know how it is now that the Swiss have the SIG 550 rifles in 5,56mm. But I'd bet it's pret' near the same.
