A Sten, MP18, MP28, MP38 or any of the other open bolt guns which origianally lacked a mechanism to lock the bolt in place could fire if: a loaded magazine was in place, the bolt was foreward, and the gun was jarred sufficiently to cause the bolt to bounce back far enough to pick up a round from the magazine. The gun would fire one round, the sear would catch the bolt when it cycled. It was patently unsafe, and contrary to training to carry a Sten in this condition. NDs did occur. The only relatively safe way to carry an early pattern Sten, with a loaded magazine in place, was to pull back the bolt and turn the handle into the safety notch. Later guns, with the so-called Mk.5 cocking handle could have their bolts locked in the closed position.
For a Sten, or any of these similar firearms to fire an entire magazine without the trigger being deliberately pressed, there are a few possibilities. The sear may be broken, so that it cannot engage the bolt. The trigger spring may be broken, so the sear is not forced into position to engage the bolt. The trigger could be tied back, with the selector on "A". The trigger mechanism could be stripped out of the gun. If any of these situations were to occur, and if the butt of the gun were jarred, the gun could run away, and fire until the magazine was empty. Tossing a Sten into a bunker makes a good story. Stop and think about it for a while. There are good reasons why it is likely just a story.
Much was said about how a Sten could fire any 9mm ammunition, domestic or captured. This is partially true. For a Sten to function properly, it requires quality ammunition intended for use in a submachine gun. The first large supply of 9mm amunition available when the Sten was coming on stream was made by Winchester. It was perfectly good pistol spec. ammunition. Sten breeching being what it was, it was not unheard of for cases to rupture. A stoppage would occur, easily cleared by cocking the gun, turning it on its side, and shaking it. Unfortunately, sometimes the bullet would be lodged in the barrel. Bulged or burst barrels resulted. When British 9mm ammunition became available, this problem was reduced.
For a Sten, or any of these similar firearms to fire an entire magazine without the trigger being deliberately pressed, there are a few possibilities. The sear may be broken, so that it cannot engage the bolt. The trigger spring may be broken, so the sear is not forced into position to engage the bolt. The trigger could be tied back, with the selector on "A". The trigger mechanism could be stripped out of the gun. If any of these situations were to occur, and if the butt of the gun were jarred, the gun could run away, and fire until the magazine was empty. Tossing a Sten into a bunker makes a good story. Stop and think about it for a while. There are good reasons why it is likely just a story.
Much was said about how a Sten could fire any 9mm ammunition, domestic or captured. This is partially true. For a Sten to function properly, it requires quality ammunition intended for use in a submachine gun. The first large supply of 9mm amunition available when the Sten was coming on stream was made by Winchester. It was perfectly good pistol spec. ammunition. Sten breeching being what it was, it was not unheard of for cases to rupture. A stoppage would occur, easily cleared by cocking the gun, turning it on its side, and shaking it. Unfortunately, sometimes the bullet would be lodged in the barrel. Bulged or burst barrels resulted. When British 9mm ammunition became available, this problem was reduced.
