I have what I think are German cartridges. The HS reads "a.u.x, St+, 1, 44 (aux = Polte Armaturen und Maschinenfabrik A.G. St+ = Strengthened steel case, 1 = Lot Number, 44 = 1942). There are a few cartridges that say 43 in the string. I’m curious if someone can tell what mechanism was used to fire the bullets. Are they collectible?