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Thread: Question about Thompson

  1. #1
    Join Date
    Nov 2006
    Anchorage, Alaska, United States

    Default Question about Thompson

    Hello all,
    A friend of mine recently inherited an auto-ordnance Thompson (semi-auto in 45 acp), I think it's the 1927 A-1 model. We were shooting it today and it was having an issue that I was hoping to get some feedback on.

    When using the stick magazine, a round would fire, the bolt would cycle and chamber another round. When using the 50 round drum magazine, 90% of the rounds fired would have the bolt lock backward similar to when a magazine was empty. The drum would still have rounds in it but it would lock the bolt.

    I didn't get as much time to look at it as I would have liked, but I should get another opportunity and was wondering if anyone has seen this problem before.

    Thanks in advance.

  2. #2


    I am not an authority on Thompsons at all but, typically when a magazine fed weapon has a fault like that it is a week spring in the mag.

    Does the mag. appear damaged or worn on the follower ?

    Does it feed reliably when the mag is full for a certain # of rounds before mis feed begins?

    Compare each mag. to the other where they enter the receiver and how well they fit the receiver, does the drum lock into the receiver as well as the stick mag ?

    Some food for thought, I hope it is of some use.

  3. #3
    Member jay51's Avatar
    Join Date
    Nov 2006
    S.C. Alaska


    Sounds like the drum either wasn't loaded right, wound-up enough, or seated properly. All three of these can cause a Tommy to lock open. The drum slides in from the side, and it can be a B**** to get aligned properly sometimes. I like the original Thompson design, short-barrel, straight-forend, and full-auto!

    Good Shootin'!



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