German sub-machine gun ammo

Dear Cracked - many moons ago I cracked the slide of my brand-new commercial P38, right out of the box, shooting British service 9mm Para ammunition. The stuff was ordinary issue Mk2Z. It was designed to work in our issue Browning SLP, better known as the Browning Hi-power or P.35 as well as our then standard sub-machine gun, the Sterling. This weapon fired from a closing bolt, called the advanced firing pin ignition system, and extracted using part of the spent gases of propulsion, so ammunition needed to be a mite stiff to make it work properly without 'double tapping'. This meant that our service pistols had to be proofed to 13.5 tons per square inch, rather than the usual 9.5 tpi of the civilian 9mm Para weapons. Anyways, it certainly disconnected by poor old/new Walther, and I eventually got a new one from the dealer, after all the paper work had been redone, a little matter of eight months, I seem to remember.