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MK40 Failure

Discussion in 'Kahr Club' started by hal13, Dec 26, 2012.

  1. hal13


    Sep 14, 2012
    I just purchased a MK40 Elite and I am very disappointed in the GUN and KAHR Service. I have previously owned three Glocks and I have never had a problem with them.

    When I went to the range the first time, I fired 200 rounds to break in the gun, and three to four times, the slide stayed back, like the magazine was empty, but it was not. I pulled back on the slide and released it and the rest of the magazine fired fine.

    I assumed this was just part of the breakin, but I went to the range yesterday, fired 100 rounds and the same thing happened two or three times.

    I am using American Eagle ammunition, and I used the same ammunition on a Glock 23 and the Glock fired 100 out of 100 with no failures, on the samr range trip.

    I purchased this gun for Self Defense, and it is not useful If I cannot depend on it.

    I called Kahr Service, and they were not helpful at all, they said if it is is working 97% of the time, it is not the guns fault. How can that be! If I am using it for self defense it must work 100% of the time like my Glocks.
    Kahr service refuses to do anything. I am suprised becasue I thought Kahr was a quality product, but obiously it is not and Kahr does not stand behind their guns.

    Has anyone else had a problem like this. I thought it might be due to a defective recoil spring but the Kahr Tech refused to do anyting, because it was working 97% of the time and he thought that was ok and not the recoil spring. I need a gun that I can count on, works 100% of the time if I am going to use it for self defense.

    Maybe I should stick with Glocks!
  2. G26S239

    G26S239 NRA Patron

    Mar 17, 2008
    Maybe have a friend of yours who is used to recoil shoot it. I am not saying you were the cause but best to have someone else try it. I have an MK9 and it runs great. That does not mean your gun is without fault but the design is sound.

  3. eltee


    Nov 25, 2006
    New Hampshire
    It's very likely that your thumb is sometimes bumping the slide lock lever. I have mine radiused at the end to prevent this.
  4. hal13


    Sep 14, 2012
    I am not exactly an inexpirienced shooter. I have shot about 12,000 rounds in the last 12 months with a Glock 21, Glock 23, and Glock 35. The last day I went to the range, after having 3 failures in 100 rounds on my Kahr MK40, I shot 100 rounds with my Glock 23, using the same American Eagle Factory ammunition with no failures. I do not find the recoil on the MK40 significantly different than the recoil on the Glock 23, although the trigger pull is significantly different. I also rented a PM40, prior to purchasing the MK40, and shot 150 rounds with no failures. So I think I can handle the gun.

    Although the design is sound, it is possilbe there is a defect in my gun. Someone on one of the Kahr forums, reported a similar problem to mine with and MK9 and no resolution.

    I really like the MK40, and it is small enough to fit in my pocket, which is why I bought it, but I need it to work 100% of the time, or it is not useful to me as a self defence gun.
  5. hal13


    Sep 14, 2012
    This is an interesting comment. The MK40 does feel different in my hand from the Glock 23 I am use to. I will make sure the next time I go shooting, I am very aware of where the slide lock is. Although I think if I was bumping the slide lock, it would happen more than 3 times in 100 rounds.
  6. fastbolt


    Jun 9, 2002
    CA Central Coast
    You right-handed? If so, consider the following ...

    Sometimes the more diminutive pistols can experience more movement within a shooter's hand under recoil, and this can cause the shooter's hand to momentarily shift position against the gun's controls (unknown/unrealized to the shooter).

    I had another instructor bring me a P239 .40 one time where the owner, and the instructor, experienced the slide failing to lock back on an empty mag. It didn't exhibit that issue when I tried the gun, though.

    When I asked the right-handed instructor to shoot the pistol left-handed, the "problem" didn't happen again. (Coincidentally, this put his strong-hand thumb on the opposite side from the slide stop lever, where his thumb could no longer rub downward against the lever's engagement surface. ;) )

    Now, I've watched other shooters sometimes unknowingly have their pistols (especially .40's) torque withing their grasp just enough so that either they strong-hand or support hand thumb bumped upward against the slide stop lever, creating what's sometimes called "early slide stop", where the slide locks back with ammunition remaining in the magazine.

    I even watched one long-time owner of a PPk/s have his support hand thumb press inward against the mag catch button, at just the "right" moment during recoil to depress the mag catch and drop the mag. :wow:

    His clenching grip and support-hand thumb just happened to momentarily align itself with the mag catch. (another right-handed shooter. ;) ) He said his Walther had been doing it for years, and he'd just accepted it happening.

    When I pointed out what his grip/finger positioning was doing and had him slightly change his grip, what he'd accepted as a long-time "problem" with the gun disappeared. He cussed himself a bit.

    Even experienced shooters may sometimes come across a particular make/model/caliber pistol that creates a minor issue when it comes to the positioning of the hand & pistol controls during the moment of recoil.

    If the MK40 doesn't exhibit the "problem" when shooting it left-handed, consider the possibility of it being a shooter-induced issue that requires some minor correction on the part of the shooter. ;)

    It happens. BTDT.

    Just some thoughts.
    Last edited: Dec 28, 2012
  7. barth

    barth six barrels

    Oct 7, 2011
    The Free Zone
    I'm dyslexic and can't possibly read a post that long.
    You have likely bent the slide stop spring during reassembly.
    It's easy to bend, especially when new, and easy to fix.
    You can order some springs from the Kahr web site.
    And you'll need one of those torx thingies (I think it's #8 or #9?).

    You have to be very careful, especially when tight and new,
    inserting the slide stop into the frame.
    Insert at about 4 o'clock part way in.
    Move slide to the correct spot.
    Then rotate the slide stop to 3 o'clock.
    And carefully push the rest of the way in.

    I did the same thing.
    BTW my MK40 Elite got much better at 200+.
    But wasn't 100% reliable until 400+.
    At that point she will feed anything and runs like glass.

    MK40's are fine weapons once you get past the break in.
    And master the re-assembly procedure.
    Good Luck

    BTW forum is a great place to resolve Kahr related issues.
    Last edited: Dec 29, 2012
  8. hal13


    Sep 14, 2012
    I appreciate your help and hope it is something I am doing wrong. Although I can get 100% of my shots in the inner 2 rings of an NRA D-1 Target with my Glocks, I cannot shoot at all left handed. I am lucky to hit the target with my left hand! :)

    I just checked my grip (with an unloaded gun in my house) and neither thumb is any where near the slide stop. I hope to go to the range on Monday, and will make sure that I watch where my thumb ends up, after recoil. I hope this is the problem, because it will be easy to fix.

    If I go to the range with my son, I may let him try 100 rounds, although then I may have to charge him for ammunition :) He has shot a couple of mags with no problem.
  9. hal13


    Sep 14, 2012
    Thanks for your suggestion. I visually inspected the Slide stop spring and it did not look bent. The part you pointed me to does not look anything like my slide stop spring. Also, according to the manual the part number should be 029M4E not 028M4E. Do you know why the part numbers in the link you gave me do not match the part numbers in the manual?
  10. barth

    barth six barrels

    Oct 7, 2011
    The Free Zone
    My gun started locking back the slide prematurely due to that part being bent. I replaced it. Am more careful with assembly.
    And the problem has been permanently solved.
    It's the spring right at the slide release hole in the frame.
    I just pulled the part number from the Kahr web.

    Do you have a MK40 or a K40???

    OK, now I'm getting mad - LOL!
    029M4E is a screw not a spring?!?!? holy crap man

    Kahr 029M4E Slide Release Lever Screw
    Slide Release Lever Spring Screw


    Kahr 028M4S Slide Release Lever Spring

    My screw takes a torx though, and my gun is a few years old.
    But I'm 99.99 percent sure that's the problem.
    I also I'm not at all confident you can just visually look at it
    and tell it's bent either. Or that your even looking at the right spring.

    The part I'm suggesting costs a whopping $6.60 plus shipping.
    Why are you still arguing with me and not fixing your gun?
    What do you have to loose?
    A McRib?

    Please view video.
    And take special care at the assembly point where the slide stop pin is inserted.
    There is a discussion about the slide stop spring.
    As well as a clear view of where it is and what it looks like.

    The break in and assembly are Kahr weak points - IMHO.
    Get by them and you will have a fine gun.
    Good Luck
    Last edited: Dec 29, 2012
  11. hal13


    Sep 14, 2012

    Thanks for your suggestion. I want to go to the range first and verify that I am not the cause of the problem, because my grip is changing and I am not aware of it.

    I do have a problem replacing parts on a brand new gun, but, if my grips is fine this is what I will try next. I will need to buy smaller Torax screwdrivers because my smallest is T10 and it is too big.

    I am confused a little on the parts, because the parts list in the manual disagrees with the parts list on line.

    In the manual, for the MK40, the slidestop is listed as part 28, the slide stop spring is listed as part 29 and the slide stop spring screw is listed as part 30, this is different than online.

    I will have to call Kahr to clarify why the online parts numbers disagree with the manual
  12. HeadShrink


    Dec 12, 2002
    Once I had the bugs worked out of mine it's been OK, but it took a little while to get used to, and work out the bugs.

    I'll tell you what I did, in hopes it helps. I ditched the stock spring and rod for the heavier Wolf spring. I did this primarily to reduce recoil, and am happy I did.

    The only time I recall the gun malfunctioning, after I had the experience with this gun to be confident I competentlyntly shooting it, was when it needed some TLC. The parts pictured above in post #10 were causing problems with the slide. I don't recall exactly, but I couldn't rack it properly at home, and it clearly wouldn't have fired right. After a smadjustmentmetightenedhted that Torx screw), and cleaning, it was all good.

    I'll be following your experience to see how it goes.
  13. ripley16


    Dec 10, 2007
  14. hal13


    Sep 14, 2012
    I talked to Kahr again and they sent me a new slide stop. I went to the range today and had 100 out of 100 shots with no problems. This is promising because I had 2 or 3 failures per 100 shots on the first 500 shots I made. I will not declare victory yet because I want to go back to the range and shoot another 100, but so far it looks like a defective slide stop was causing the problem,
  15. HeadShrink


    Dec 12, 2002
    Glad to hear you might be fixed. For clarity, what were we thinking might be wrong with the slide stop (frozen rotating part)?

    EDIT: My bad, I was thinking about the other thread related to a problematic slide stop/pin. I'm back with you.
    Last edited: Jan 13, 2013
  16. Sgt127


    Nov 5, 2002
    I bought a brand new, old stock K40. First few hundred rounds, it ran great. Then it started locking bag during a string of fire. I assumed it was my thumb. Tried left handed for awhile, still did it. I then looked at the bullet that should have chambered and found a ding on it that corresponded with the slide stop. Ordered a new slide stop. Same problem. Sent it to Kahr, new slide stop and a note that it was test fired and working properly.

    No. Still doing it. Same ding on the bullet. Bought two brand new mags, still doing it, a lot. Like every 15 rounds or so. It's about to go back to Kahr. I'm convinced, something is out of alignment and, the rounds are just too close to the slide stop. There is very little room in there if everything is working right.

    If they can't fix it or replace the pistol, I may just grind off the stop. I tried filing one down until it barely engaged the tab on the follower, and, it would still hit. I would rather the gun close on an empty chamber than stop on round 2-4-5 whatever.