Although the 9mm parabellum cartridge had been around since the turn of the century, the British army did not start using it in its service weapons until the Second World War. It was only after the outbreak of war that Britain started developing the sub machine gun and it was this weapon in particular that popularised this cartridge in British service. Although the British had to accept the .45 ACP round to accompany the Thompson SMGs they purchased from America, it was far more practical to use 9mm ammuntion in home grown SMGs.
Not only was the 9mm an excellent cartridge that combined a good balance between weight and velocity, the design work had been completed decades before and there was a good understanding of its ballistics. Secondly, using a common cartrige with most continental SMGs and pistols meant that captured ammunition could be used if necessary.
The first British 9x19mm ammunition was produced in September 1941 and in December 1941 a modified cartridge known as the “Cartridge, S.A. Ball 9mm Mark 1z” was approved:
This particular round was manufactured in 1942 and the markings on the bottom indicate that it was produced by the Royal Ordnance Factory at Blackpole:
Note also the purple annulus that was introduced at the same time as the Mk1z was adopted. By 1943 the ammunition had been updated again to Mark IIz which used a different propellant charge.
These rounds were issued for use with Sten guns, the Lanchester sub machine gun and the Browning Hi Power pistol and were produced in huge quantities. Although not rare, it is always nice to find wartime dated rounds and this is a very nice early example.