The STEN was the gun that jammed at the Reinhardt Heydrich assassination back in WW2 in in Prague, Czechoslovakia in 1942, I believe, Fortunately, the other member of the team (who were CZs, trained in GB) threw a grenade that killed him a week later, maybe because refused to let anyone but a German doctor treat him.
I would like to see the Stens tested against other sub guns of that time. I think they were the cheapest guns. They were small, concealable, apparently accurate and most of them reliable. Just not one. The assassins were killed in a church where they went for shelter.
His death was followed by the total destruction of the village of Lidice in retrobution. All the males over 15 years were shot, the women put in concentration camps where most died. All buildings were razed and the landscape was leveled.