M3A1 question ...finger in the hot bolt!


Apple a Day
January 26, 2003, 03:30 PM
I have a question regarding the M3A1 submachine gun used by the U.S. during WWII and beyond. The A1 version did away with the charging handle and had a hole in the side of the bolt the shooter would stick his finger in to actuate it.
Was there a bolt release switch? Did it lock open on an empty magazine? I am curious because that would sort of imply that without one the shooter would have to stick his finger into a hot bolt to clear a dead round, charge the gun with a fresh magazine, etc... Was that the case? Also, how well did this work with gloves/arctic mittens? :confused:
Thanks in advance.

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January 26, 2003, 03:55 PM
The hole was pretty big. Gloves were no problem.

You'd have to be shooting one heck of a lot for the bolt to get hot.

The bolt stays to the rear. This is an open bolt gun, and every time the bolt goes forward the round fires. The bolt release was the trigger.

January 26, 2003, 07:51 PM
As above, the M3A1 is an open bolt gun. You pull back the bolt to cock it, when the trigger is pulled, it slams shut to chamber and fire the round.

There is no bolt hold open on an empty magazine.

When empty, a fresh mag is inserted, and the bolt must be re-cocked. This is how MOST SMG's operate.

Few firearms work well with mittens, but the cocking hole in the bolt, and the large trigger guard work well with gloves.

The grease gun has a low cyclic rate, and heavy magazines, which limits the amount of ammo that can be carried. This limits how much/fast it can be fired. All this, in conjunction with the massive bolt and sheet metal receiver tends to keep the bolt from getting that hot.

Jim K
January 27, 2003, 01:34 AM
Another note on the M3/M3A1. The safety is the cover. It can be closed with the bolt either cocked or full down, but if the bolt is cocked, a projection on the inside of the cover fits into a hole in the bolt and holds it back and off the sear. If the bolt is not cocked, it cannot be cocked either manually or by intertia if the cover is closed. If the bolt is cocked, the gun is ready to fire when the cover is opened.

Just FWIW, some SMGs do lock open on an empty magazine, most notably the Thompson, which locks open on an empty stick (20 or 30 round) mag, but not on a drum. With a drum mag, the gun has to be cocked by hand, the magazine release pressed upward, and the drum slid out to the side.

The bolt on the STEN and MP.38/40 can be locked back manually and that is the only actual safety. The later STEN and MP bolts can also be locked in the forward position on an empty chamber, done so inertia would not fire the gun if the butt were being used as a battering device.


Apple a Day
January 27, 2003, 06:30 AM
Thanks for all the info. I didn't realize that the M3 fired from an open bolt, shoulda figured.

Johnny Guest
January 29, 2003, 12:52 PM
Another footnote to the STEN gun - - -
In the interests of safety, unless actually in enemy contact, usual procedure was to carry with bolt forward, and then an empty magazine inserted. There were suposedly several instances of guys jumping off back of a vehicle with the STEN slung, barrrel upward, and causing accidental firings. Mass of the bolt would come back far enough to pick up a round from the mag, but not far enough to catch the sear. this would probably be disconcerting to the next guy on the bed of the truck. :(
Turned out, it was actually safer to carry the early guns cocked and in safety notch. Later mods addressed this issue with a forward safety notch.

I wonder if early experience with the STEN had anything to do with the port cover/safety design of the US M3 series?


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