I recently picked up an MK9 and am experiencing problems with the slide locking back while there's still rounds in the mag.  I called Kahr and the guy I spoke with told me I must have bent the slide stop spring by installing the slide stop incorrectly .  He said he'd send me a new slide stop spring and to look at the disassembly/reassembly video on their website for how to properly install the slide stop.  Well I watched the video and that's exactly how I installed the slide stop.  The slide stop also doesn't look bent, see below pics.  I received the new slide stop spring and it looks the same as the original one, but I haven't installed it yet to see if it makes a difference.  Kahr also said not to use loctite on that screw that holds the slide stop spring in place, but I'm not sure why that would be bad to do...thoughts on that?

Anyone else ever experience issues with premature slide lock or have any ideas what could be causing it?

If the wrong grade of Loctite is used the screw head might snap off the next time someone try's to remove it. Likely they have figured out it is not going to back out in normal use.

Not uncommon for the thumb of a right hand shoot to bump the slide stop when shooting. Small gun and big hands increase the chances.

I checked my PM9, but it is done differently so no help there. In the video the spring and it is hard to see, looks like it does not sit on the lip like your does. I am talking about the right side of the spring, pointing to the right and the lip just under it. In the position I see it in on your picture, I would think it would be putting more downward force on the slide stop than in the video.

With your gun assembled and the slide forward do you find that the slide stop is firmly directed away for the slide or is it flopping up and down easily. I know kind of subjective.

With the slide off and the pin inserted in the frame maybe you can look from the other side and see some anomaly with the interface of the spring and slide lock.

Mike

Thanks for the reply, I was beginning to think no one ever would .  I'm a lefty so I'm not accidentally hitting the slide stop while shooting.  Slide stop spring does look to be working properly.  It stays in the down position and with the slide off and slide stop installed there is tension on the slide stop keeping it down.  

From my eyes, the spring in the video looks identical to mine at 4:12.  It looks like my slide stop spring is resting in the right spot noted at 4:25 as shown in the second picture and I installed the slide stop the same way they did in the video (not sure how else you would install it).

Can anyone else with an MK9 comment on whether their slide stop spring looks the same or if anything looks off in my pictures?  Has anyone heard of this problem before?

https://youtu.be/zXmSCnIOaUk?t=4m9s

Silly me. I just figured out your 2nd picture is with the slide stop installed without slide and can see the spring and stop contact. Looked at that picture several times and really never 'got it' until now. Hard to trouble shoot from picture. Sold my MK9 a few years back and having 2nd thoughts about that. Anyway, looks like spring sits high on the stop toward the centerline of the frame. I wonder if possible it slips off during firing and the only clue would be to notice the downward tension is missing or weaker than before. Maybe tweaking it downward in the 2nd picture getting it to normally rest in a way to make it more difficult to slip off the top edge. Maybe the Kahr tech was talking about bent in the 2nd picture vs. in the 1st. I was thinking 1st picture all along until I figured out what the 2nd picture was showing. From both pictures it looks like the downward force should be good (pic 1), but possible it slips off during firing (pic 2).

Mike

Pass #2:

I broke my PM9 down and took a look at the pin in place with the slide off. As I push the pin into place the spring rides up a ramp to the flat and then pops into a "V" groove that the spring sits in. In my case the spring when in the groove is next to the wall which is the bottom surface just below your 2nd picture. I can't see the detail in your 2nd pictures but it looks like the spring in picture 2 is not in the groove if there is one and clearly is not next to the bottom wall. I don't really know if that could be causing your problem, but at this point that's about all I see that looks suspicious.

Really frustrating to have the slide hold open with rounds in the mag. Hope you get it worked out.

Mike

P.S. Being a lefty is not a bad thing, takes the 'thumb' issue us ham handed righties have to deal with.

Thanks for looking into this for me.  I guess the MK9 slide stop is different than the PM9 since mine doesn't have a groove for the spring to rest in, it just has a flat surface, see below pic.  I don't think the spring slipped out of place because when I had the slide lock back prematurely, all I had to do was pull back a little on the slide and the slide stop went down under spring tension.  Still not sure what's going on with it; I guess I'll just install the new spring Kahr sent me even though it looks identical to this one and see how it goes.  Would be rather annoyed to blow through a lot more ammo testing this new spring if that's not really the problem...

First attempt at adding pictures and so far it looks OK in preview. Your pictures had enough resolution I could copy an area and edit which I didn't think would work at first.

"A" is the burnish mark where the spring normally rides. Which I think is closer to the edge where the ramp begins than it should be. Kahr addresses this by notching the flat surface on the PM9 in the center of the flat surface. Which holds and keeps the spring in position.

"B"  looks like another smaller burnish which could be the result of disassembly/assemble. Or could it be the result of the spring falling off the flat surface and riding on the slope of the ramp resulting in less downward force allowing the slide stop to engage before the magazine is empty. Riding on the slope may be difficult to identify as it could be possible that holding the slide open clears the original fault and you find the spring on the flat.

"C" is my attempt to show where I think the spring should be riding closer to the vertical wall which in the picture is a thin dark line from left to right. This could be what the Kahr tech was talking about when he said spring was bent. Bent in the upward direction close to the drop off for the ramp. Having a replacement spring I would bend the original down as shown in "C". Grasping the spring at the tip bending down so that when the stop is in position the spring is in the position of the red line.

P.S. Should have asked before. Is it always the same number of rounds in the mag and how many? If more than one mag is it always the same one or both?

Wow, that's some detailed analysis.  That "B" area is from re-assembly as the spring needs to ride up the slope to get onto the flat surface.  Strange that the MK9 slide stop doesn't have a groove in it like your PM9.  

Well I just put the replacement spring on that Kahr sent me and it does ride further away from the frame that the initial spring.  I guess we'll see how it goes when I try it out this weekend.  I'm not sure how the first spring got bent or if it came like that from the factory since I installed the slide stop exactly as they show in the video...and there's really no other way to do it.  So hopefully this spring stays in place.  

The premature slide lock was only happening with the 6 round mags and not the 7 round mags.  I should have marked them before shooting, but I did note which mag was used the last time I had the premature slide lock and have now numbered the mags to see if it's only that one causing the problems.  The mags had somewhere around 3 or 4 rounds left in them when it happened.

Oh and I also don't know why Kahr decided to write "7" on the inside of my frame

I recall that the PM9 followed the MK9 and the groove may be a design improvement. I like where the replacement spring is now positioned. Hopefully that will put a end to premature stoppage.

Three or four rounds left takes the magazine follow out of the picture. If it were always one round left it could be the tip of the follower out of position (bent) engaging the stop to soon. Not sure what to make of the 6 round and not the 7 round having problems. The 7 round does let you get a better grip which should lessen the muzzle flip. If the old spring was out of position the resulting weaker downward force might allow the stop to engage when using the 6 round mag.

Intermittent problems are always difficult to solve. Seldom is the cause of the problem black & white.

Good Luck

Mike

Well as I suspected, the new slide stop spring did nothing and I'm still getting premature slide lock.  Time to call Kahr CS again...

Russell92,

I was so hoping your next report would be positive. You might have to send it back. See if they will pony up a paid shipping label if you ask real nice.

Mike