Despite its tendency to jam, the Sten Gun's simplicity allows it to operate in harsh conditions with very few probabilities of breakage. And even if one did break, spare parts are more than plentiful.
The Sten Gun Mk 2 is a 9x19mm submachinegun famed for being "cheaper than a box of shoes". It was the standard British submachinegun for WW2, but armed many countries in the Allies too, both during and after the war. Hundreds of thousands have been imported or manufactured in Oceanyka.