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Thread: Diagnostic help: PX4 trigger drag in single action

  1. #41
    Quote Originally Posted by Earlymonk View Post
    By this: http://www.berettasupport.com/applic...search_new.htm
    And by the slide IT date:

    2017
    Nice Avatar.

  2. #42
    The IT date will say when the slide was manufactured. It will be an approximation of when the pistol was assembled. The serial number can tell you when it was assembled.
    If we find that there is a similarity of dates, then we can check the frame lot numbers and if we find a similarity we may find a problem that Beretta can address.

  3. #43
    Member
    Join Date
    Mar 2017
    Location
    Czech Republic
    One data point from my side, I have experienced the same grittiness on my PX4 manufactured in 2014, specifically when manually cocking the hammer and applying pressure on the trigger, and to a lesser extent approximately in the middle of the DA stroke (during the DA stroke there was no squeaking but the grittiness was noticeable, starting approx at 1/3 of the pull and disappearing for the last third of the pull before hammer release).

    Upon inspection of the frame, looking from the top at the trigger bar, it looked to me as well as if the trigger bar is making contact with the hammer pin retaining spring, and it looked like the spring is misplaced since it had a lot of free movement when touched with a small screwdriver. Keep in mind up to this point I never fully disassembled the PX4 frame.

    Upon disassembly of the frame and inspection of wear on the trigger bar and spring, I noticed the trigger bar, in the portion of the pull that interests us, is sliding against the head of the pin/stud (for lack of a better word) that is used to secure the hammer pin retaining spring. This looks like is a removable part but in the factory drawing it looks like is considered an integral part of the hammer unit housing. Out of curiosity, I've lightly polished the head of this pin, as well as the affected part of the trigger bar, and it DOES improve on the feeling of the trigger. It looks like to completely eliminate the squeaking after manually cocking the hammer, one would need to sand away approximately 0.5mm (pardon the EU unit of measure, approx. 0.02 inches) of material from the head of that pin.

    I did not proceed further with experimenting or with sanding/polishing since in my opinion this is not a big deal (I could only feel it during dry firing AND paying attention to it) and IMHO it looks like it doesn't affect the functioning of the gun in any way. In fact the issue, if unnoticed, may go away simply by cycling the trigger enough times when firing ?

    Photos of the pin head below, marked in red.

    Name:  px4_1.jpg
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  4. #44
    Quote Originally Posted by m.mancini View Post
    One data point from my side, I have experienced the same grittiness on my PX4 manufactured in 2014, specifically when manually cocking the hammer and applying pressure on the trigger, and to a lesser extent approximately in the middle of the DA stroke (during the DA stroke there was no squeaking but the grittiness was noticeable, starting approx at 1/3 of the pull and disappearing for the last third of the pull before hammer release).

    Upon inspection of the frame, looking from the top at the trigger bar, it looked to me as well as if the trigger bar is making contact with the hammer pin retaining spring, and it looked like the spring is misplaced since it had a lot of free movement when touched with a small screwdriver. Keep in mind up to this point I never fully disassembled the PX4 frame.

    Upon disassembly of the frame and inspection of wear on the trigger bar and spring, I noticed the trigger bar, in the portion of the pull that interests us, is sliding against the head of the pin/stud (for lack of a better word) that is used to secure the hammer pin retaining spring. This looks like is a removable part but in the factory drawing it looks like is considered an integral part of the hammer unit housing.
    An excellent observation. It is also a very frequent culprit. You are also correct that it is not a user replaceable part (semi-permanent installation). Since many Storms don't squeak or rub, it is possible that something in the frame is pushing it to rub too hard on this peg. The trigger bar drag marks might suggest that this is what pushes erring trigger bars down. That remains on my primary suspect list.

    Light polishing, as you mentioned, can surely help if done carefully. This peg also serves to maintain the trigger bar's alignment with the hammer and sear. If too much metal is removed, misalignment could occur. Dropping some oil to drip down the trigger bar to this area could help a person determine if their pistol is being affected by this rubbing.

    The good news is... on all of my PX4s with moderately high round counts this area self polished pretty well.

  5. #45
    Member
    Join Date
    Mar 2017
    Location
    Czech Republic
    Agree, after spending some more time looking at the PX4 trigger group, it is definitely a bad idea to do anything more than a light polish in that area, since it keeps the trigger bar from flexing and in alignment, as you said.
    I'm about to order a competition trigger group anyway, curious to see if it will solve the issue with the sticky trigger bar. If not, no big deal.

  6. #46
    Quote Originally Posted by m.mancini View Post
    Agree, after spending some more time looking at the PX4 trigger group, it is definitely a bad idea to do anything more than a light polish in that area, since it keeps the trigger bar from flexing and in alignment, as you said.
    I'm about to order a competition trigger group anyway, curious to see if it will solve the issue with the sticky trigger bar. If not, no big deal.
    Cool. I would be curious how the Competition Trigger group affects things.

  7. #47
    @m.mancini , If you still have your hammer assembly out, could you inspect the cut out in the frame where the trigger bar rides for anomalies?

  8. #48
    Member
    Join Date
    Mar 2017
    Location
    Czech Republic
    Quote Originally Posted by PX4 Storm Tracker View Post
    @m.mancini , If you still have your hammer assembly out, could you inspect the cut out in the frame where the trigger bar rides for anomalies?
    Looks clear of defects/burrs.

  9. #49
    Food for thought about this trigger sticking...

    When the hammer is pulled back by hand or by the slide, the hammer’s cocking cog pushes the trigger bar downward and forward.

    See- https://pistol-forum.com/showthread....art-do-and-how post #3, bottom most pointer & post #4- top picture, right pointer.


    This keeps the trigger bar from accidently bumping the sear while being thrown forward. https://pistol-forum.com/showthread....-and-how/page2 post #17

    When the trigger moves forward it lets the trigger bar pop up (with a slide in battery or no slide on). If the trigger bar’s peg is relieved of that pressure (from the hammer) it pops up.

    If the hammer's work space and the trigger bar’s are impeded with burrs or excessive debris, the trigger bar could get stuck there, creating a “sticking trigger” during reset. https://pistol-forum.com/showthread....-and-how/page2 post #13
    Last edited by PX4 Storm Tracker; 04-26-2018 at 01:07 PM.

  10. #50
    Member
    Join Date
    Aug 2017
    Location
    Central Texas
    Not normal. Assembled incorrectly? Google Px4 disassemble/re-assemble and carry it out with your pistol would be my suggestion. Possibly the trigger bar spring? Needs a lot send back to BUSA if this doesn’t get resolve it or you don’t want to play gunsmith.

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