USP Trigger Problem
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Thread: USP Trigger Problem

  1. #1
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    Default USP Trigger Problem

    Hey guys I have a KD date code USP 9mm that I converted to LEM. However I decided to go back to DA/SA using updated internals. So I bought the latest sear, hammer, catch, hammer axle, etc. and installed them.

    Now SA works fine and DA works as long as I use the decocker, but if I dry fire the gun there is no second strike capability anymore. Now maybe I'm not remembering correctly but I could have sworn that it had second strike capability with the original parts and now I'm second guessing myself.

    Anyone know what I might have done wrong here?

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    Quote Originally Posted by tphelon10 View Post
    Hey guys I have a KD date code USP 9mm that I converted to LEM. However I decided to go back to DA/SA using updated internals. So I bought the latest sear, hammer, catch, hammer axle, etc. and installed them.

    Now SA works fine and DA works as long as I use the decocker, but if I dry fire the gun there is no second strike capability anymore. Now maybe I'm not remembering correctly but I could have sworn that it had second strike capability with the original parts and now I'm second guessing myself.

    Anyone know what I might have done wrong here?
    IIRC you need to get the Old Style Hammer & Catch. Not sure about the Sear & Hammer Axle, but I would have used the ones that were in the KD Date Coded USP just to be on the safe side.

    Stay tuned for more input from other members!
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    Until TooSixy shows up to give a definitive answer, I'd suggest going back in and verifying all of the spring legs are in the right places, and the disconnector and trigger bar are functioning correctly (I'm assuming the trigger bar detent and spring are correctly installed).

    The lack of the trigger bar re-engaging for the second strike (which is a capability the USP DA/SA definitely has) suggests a spring or a component is mispositioned such that the end of the trigger bar is not rising back into position to be able to re-engage and draw the hammer back. Maybe the trigger bar is displaced slightly to the left, so it's no longer resting on its detent? TBDS missing?

    Shots in the dark, but at least a starting point.

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    Quote Originally Posted by mneblett View Post
    Until TooSixy shows up to give a definitive answer, I'd suggest going back in and verifying all of the spring legs are in the right places, and the disconnector and trigger bar are functioning correctly (I'm assuming the trigger bar detent and spring are correctly installed).

    The lack of the trigger bar re-engaging for the second strike (which is a capability the USP DA/SA definitely has) suggests a spring or a component is mispositioned such that the end of the trigger bar is not rising back into position to be able to re-engage and draw the hammer back. Maybe the trigger bar is displaced slightly to the left, so it's no longer resting on its detent? TBDS missing?

    Shots in the dark, but at least a starting point.
    The detent and spring are definitely in there, I know because I launched them out at one point and had to go find them. The bar seems to be doing what its supposed to but its just not engaging the hammer. Maybe they changed the trigger bar at some point too?

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    Did you use the right catch ?

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    I just put my usp back together and I know it would be easy for the plunger to "slip" out and around the back of the trigger bar upon reassembly (when you put hammer and hammer axle in over it) like mneblett said. I don't know if that could cause your symptoms

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    Quote Originally Posted by Kost View Post
    IIRC you need to get the Old Style Hammer & Catch. Not sure about the Sear & Hammer Axle, but I would have used the ones that were in the KD Date Coded USP just to be on the safe side.

    Stay tuned for more input from other members!
    Yup, this.

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    Quote Originally Posted by dano1200r View Post
    Yup, this.
    What's the reasoning behind that? I'll try it but the current hammer and catch are the correct pieces for each other, it doesn't make sense that only the old style hammer and catch would work.

    It seems to be a problem with the trigger bar not engaging whatever its supposed to engage to cock the hammer for a second strike. To me that makes it seem like a trigger bar, disconnector, or control latch problem.

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    I still don't know what was causing my problem, so I reinstalled the original parts and everything is working fine now.

    I tried a few combinations of old and new parts and it seemed each one had a different problem.

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    Quote Originally Posted by tphelon10 View Post
    What's the reasoning behind that? I'll try it but the current hammer and catch are the correct pieces for each other, it doesn't make sense that only the old style hammer and catch would work.

    It seems to be a problem with the trigger bar not engaging whatever its supposed to engage to cock the hammer for a second strike. To me that makes it seem like a trigger bar, disconnector, or control latch problem.
    My reason was you were using in the OP the new parts, while the old is what was needed to be matched back up, which is what you have apparently done. Happy shooting.

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