(pics added) Some trigger issues resoved today

[CJB]

Been home sick.

Had a chance to really get into the triggers of one of my PM45's and the PM9.

Issue for both - (on unloaded pistol)
Rack slide
Pull trigger
Hold trigger fully rearward
Next rack is really hard, as if the slide was "locked"

The issue is the cocking cam's striker unlock lobe forcing the unlocking piece fully into the slide's opening, and wedging the slide in place because of that.

I did a lot of comparison against the PM45 that didn't have the issue, which by the way, is the one that Kahr worked on when it was new. That pistol shows signs of handwork on the unlocking lobe. I checked the unlocking piece depression.... even took all three slides apart and cleaned everything to make sure dirt and grime weren't clogging things. It wasn't.

I also looked at how much of the unlocking piece was protruding inside the slide when fully depressed. There was a slight difference between 9mm and 45acp, but both 45's were the same.

Decided to trim the lobe on the PM45. Using a Grobet warding file, only about 1/4 inch wide and 3/4 inch long, and slowly, evenly.... reduced the lobe. Tried it. Better, but not perfect. A little more.... tried it. Perfect. Did a quick Cratex wheel polish and called it done (after a cleaning).

Also, did the pencil test....and it launched a half length Columbus 1492 #2 pencil half way across the room. So, the striker is unlocking ok still.

The result was so nice, I had to do the 9mm too.

Results equally the same.

I don't think the cocking cam is all that hard, or case hardened, since it cut very easily with the file. So, I don't think there will be a wear problem.

Also gotta say, the problem I had (and others have had) should not show up in live fire, since youre slide will begin to move as the trigger also moves to its rearward point. In live fire, you'd likely never have the trigger back fully and the slide stil 100 percent in battery.

Proceed at your own risk.

[jocko]

so what ur saying is u fixed sumpin that really didn't need to be fixed if used correctly???

[CJB]

Of course! ;-)

Jocko, how could I have a PM-9j model, your namesake, and not have it perfect in every way? Hmmm?

Seriously....you hear stories of triggers not releasing the striker. I'm wondering if there's crap getting under the unlock piece, prevening the trigger from moving back far enough to do its job. That makes me go hmmm too.

Things gettin' fixed that work right if used correctly, but really... just aint right.

Such as - the fingernail on the end of your little finger.

If used correctly, it just sits there like it ought to. Buf unless you got it trimmed out just right, its not gonna be able to snag that booger outta yer nose, or... its gonna rip through your nose and maybe take out an eye, from the inside out! You gotta have it trimmed "just so" to avoid those extremes.

[b4uqzme]

^^^^ good advice about that finger.. Just sayin'.

[JohnR]

I noticed the exact same thing with my PM45 after I beveled the stripper. I'll probably leave it alone since all those tool names sound foreign to me. Wouldn't wanna gouge my eye out.

[CJB]

Only happen if you didn't trim yer little fingernails

[muggsy]

With a honker like mine you use your thumb. :)

[jocko]

Of course! ;-)

Jocko, how could I have a PM-9j model, your namesake, and not have it perfect in every way? Hmmm?

Seriously....you hear stories of triggers not releasing the striker. I'm wondering if there's crap getting under the unlock piece, prevening the trigger from moving back far enough to do its job. That makes me go hmmm too.

Things gettin' fixed that work right if used correctly, but really... just aint right.

Such as - the fingernail on the end of your little finger.

If used correctly, it just sits there like it ought to. Buf unless you got it trimmed out just right, its not gonna be able to snag that booger outta yer nose, or... its gonna rip through your nose and maybe take out an eye, from the inside out! You gotta have it trimmed "just so" to avoid those extremes.

worst habit one could ever have and I have no finner nails. U know I meant no disrespect toyou but CJB u have abilities over 90% opf us here, and what sounded simple to you would be a major fokk up for most with no gain. Sh!t I never heard of those tool names. Just sayin. No doubt we can make things better sometimes as u did, so take my comment with a grain of salt, no more no less. :Amflag2:

[skiflydive]

Evidently CJB is not a big Wally World shopper. You can't buy Grobet or Cratex products there. Those are for people who know what they're doing and appreciate fine tools.

[CJB]

Stock dremel rubber wheel would do, but Grobet files are priceless.

Think in terms of $35 for a file as wide as a wooden coffee stirrer, three quarters of an inch long, with teeth that cut, not slide. True gems. Most folks cant work a file because the file is unworkable....

[CJB]

I'll do some pics later

[CJB]

As suggested earlier, some pictures.

Below you can see the slides locking plunger, which locks the striker. If your pistol is exhibiting the sticking problem, or if you can not get the trigger to release the striker, I'd check for debris and grime under that plunger. Before making any adjustment, inspect the plunger to make sure it depresses to be flush, or quite nearly so, with the inner surface of the slide, as shown.http://img.photobucket.com/albums/v214/bandersnatchreverb/Firearms/IMG_20140516_171751_zps44747db1.jpg (http://smg.photobucket.com/user/bandersnatchreverb/media/Firearms/IMG_20140516_171751_zps44747db1.jpg.html)

Here you can see the rework of the unlocking lobe on the cam. Folks say "I removed one or two thousandths" because they have no clue as to how big 1/1000 inch really is. I do. I'll estimate that I took off ten to twelve thousandths. Thats one to one and a quarter hundredths of an inch. Not much, but more than the oft told "one or two". I tried to keep the profile rather flat topped as the original, but did put a little rounding on the edges (hard to help doing that actually).
http://img.photobucket.com/albums/v214/bandersnatchreverb/Firearms/IMG_20140516_171623_zps3270cd27.jpg (http://smg.photobucket.com/user/bandersnatchreverb/media/Firearms/IMG_20140516_171623_zps3270cd27.jpg.html)

The result is a unlocking piece that does not wedge the slide into place with the trigger fully rearward. It also unlocks when it ought to, releasing the striker for firing. I tested quite a lot, and the pistol(s) are unlocked at the moment of stiker release, not after (which worried me). I had to put some shim material in back of the trigger to do that test, so the trigger would not continue rearward after releasing the striker. We're ok in all reagards of unlocking the striker.

And below, a shot from today of my slide stop. This is the ground pin, in a mim lever, held in place by a cross pin. You can see the ground pin is nickle plated, and where I reworked it, the plating was removed, and it oxidized black in my pocket. The steel is of such hardness and toughness that it has not pitted substancially, but has sort of "rust blued" with the humidity in its carrying environment. Even the cross pin is not stainless, and has darkened.
http://img.photobucket.com/albums/v214/bandersnatchreverb/Firearms/IMG_20140516_171540_zpsbdac3087.jpg (http://smg.photobucket.com/user/bandersnatchreverb/media/Firearms/IMG_20140516_171540_zpsbdac3087.jpg.html)

[kerby9mm]

I had that issue with my mk9 3 years ago & kahr fixed it. When I noticed my mk40 didn't catch with the trigger pulled I compared the two & noticed the cam rose slightly above the frame rail whereas the Mk 40 did not go above the frame rail. I has several posts on this.

[CJB]

You're probably one of the posts I read in researching the issue.

In that case, THANKS!

Caution though.... its not really a matter of "rising above the frame" or "being flush". All three of mine rise a little above the frame's upper edge.

I'm wondering this is a place for stacked tolerances to become evident. You've got the cam, the slide, the locking piece, the hole in the frame for the cam pin, fit of slide to frame, and trigger bar, and trigger over travel..... ?

[muggsy]

You're probably one of the posts I read in researching the issue.

In that case, THANKS!

Caution though.... its not really a matter of "rising above the frame" or "being flush". All three of mine rise a little above the frame's upper edge.

I'm wondering this is a place for stacked tolerances to become evident. You've got the cam, the slide, the locking piece, the hole in the frame for the cam pin, fit of slide to frame, and trigger bar, and trigger over travel..... ?

There is no such thing as stacked tolerances. Tolerances are tolerances. If tolerances are stacked in either direction the parts should still work together, because they will still be within tolerance. That's how the concept of mass production came into being. If the parts won't work together when stacked the tolerances of the individual parts are too great or too little. You don't hand fit parts in mass production.

[CJB]

Mugs ol' bean, thank you for idealist view of production. In my world, I deal with what we (and you) would hope are deisgns and specifications that work on the production floor. Then... I've got to deal with several dozen vendors of parts, our own production, and all the crap never envisioned, by anyone, be that in the deisgn, outsourcing or assembly stage. And production has got to continue, because the products must contnue to flow into nice little brown boxes, and out to distributors worldwide.

Right now I'm dealing with DuPont, who has discontinued a certain Delrin, only to replace it with an improved Delrin, whose properties are superior (they say). One minor change, has resulted not in dimensional imperfection, but a shift in the wet friction of a buna-n seal against a delrin cylinder.

Stacked toloerances do exist in production Mugs. I live it every day, and my customers suffer because of it. There are things not thought to be critical, that turn out to be critical. There are the unforseens. Nothing is perfect, no process is perfect, and few designs are perfect in that their fault tolerance is beyond some sort of issue.

What happens is.... the bean counters get into the picture. We hope to gauge parts from every vendor, but cannot gauge every part for every tolerance. That is beyond production capability. We'd be like the change-bank. We spot check. If there's a known really touchy area, we try to find a way to not gauge, ie, applying a TLC method in parts post production (as we do with those Delrin cylinders). So, lets say we get a part thats maybe a little out of spec. Production continues with the out of spec part, as the rest of the assembly will accept the part and function as it should. Well bean counters love this. We don't stop production, and we get to haggle the vendor down a bit, after the fact, which is good (and good for the vendor since he doesn't get a scrapped lot of parts back on his loading dock). So.... now we get another similar off kilter part, and another.... bean counters having a field day.

This is my real world of production life! Pretty soon.... you get the right combination of parts that wont work. Bound to happen. Then all hell breaks loose and we try to find the ONE part we can scurvy to get back into proper product operation, rather than go after all of them at once. Why? Because we gotta keep the product goin' out the door, thats why. Is it mission critial to get it right? Of course. But its even more critical to put the product into the end user's hands. There is a corporate image of always being available to uphold. And so.... my little world of stacked tolerances is a real one.

I'm glad they don't exist in your world!

[CJB]

Not sure how much Saeilo/Kahr actually manufacture, or just outsource and assemble. Trade secrets I guess. Certainly they have to deal with vendors. They've stated in the past that the poly frames are outsourced - but to what extent is the work done by the vendor? Dunno. I seem to recall the also stated they make the slides, and do final machining on the barrel (even though they sort of mis-state things a bit in the 3" blank part). Broken follower folks would question the barrel machining part.....

Anyway, all I'm saying is, Kahr is a real production outfit, that works with real vendors, who introduce real issues that individually may be accepted, but upon correct alignment of circumstance, do not make for a perfect situation. This is known as stacked tolerances in the real world of production.

Think of it this way - if everything were perfect, we'd all be here and rejoice at the wonder of Kahr, not wonder when we'd be able to rejoice about Kahr! Not gettin' down on Kahr at all.... great design, great product, great pistols. I trust my life to one every single day, thank you Justin Moon.


ps - I'm wondering why nobody has stated the obvious. Kahr pistols were designed by a Kook! What'd you expect???!!!!