CM9 nosediving fixed!

[jeffe007]

I can now slingshot my CM9 with any round and no issues. The culprit was the hold-open device thats attached to the slide stop. If one holds the slide open and looks down into the breach from above, one can see it sticking out into the pathway of the projectile from the left side of the slide. Not sure what to call it but it is definetely attached to the slide's hold open.

I noticed that it was intruding into the projectiles pathway and the first movement it caused when contact was made was, to push the bullet down. Upon the bullet's continuing pathway into the barrel breach, it's trajectory moved a 2nd time. This time it moved to the right just enough to make contact, head-on, with the right side of the feed ramp.

So, w/ 600 grit sand paper and finishing w/ 1500 grit paper, i slowly sanded that little protrusion and voila! now, i have zero feed issues! its great!! i think this protrusion is some sort of guide but it seems to be too big. anyway, its a FWIW sorta thing.....

[Benaiah]

I'd love to see a picture showing your modification... Thanks for the info.

[Steeltoes]

I'd like to see a photo too...please post....:)

[TucsonMTB]

Yeah. I always sand down the slide lock actuator on all my Kahr .40 S&W mags. It's really obvious about catching, even when you are just loading the magazine, until you sand it down. My most reliable magazine occasionally fails to lock back at the end of magazine as a result, but that beats the alternative . . . nose diving. :eek:

I wish Kahr could convince the Tripp Research people to produce a version of their follower for Kahr magazines.

http://www.trippresearch.com/PDGImages/folh45.jpg

Notice how the metal insert is perfectly flush with the wall of the follower. That design really works well in my 1911 magazines! :D

[Popeye]

I had a similiar problem with my RIA 1911. The slide lock had a little burr on it that would catch the round coming up and out of the mag and put the slide lock on and held the slide in the open position. Took a little emery paper and took the little burr off and never had a problem again. With the CM it's nose diving the rounds. I could see where that could be a problem with nose diving the rounds or possibly holding the slide open prematurely.

[JBarbaresi]

very interesting and good to know. i haven't had any problems with the slingshot but i do need to make sure i pull the slide all the way to the rear and release it with some authority. i also found that applying some pressure forward simlutanously to the release helps in the process as well.

how far down did you sand that tab and did you keep the angles the same? it definitely does appear that it is there to guide the round into the chamber.

[TucsonMTB]

how far down did you sand that tab and did you keep the angles the same? it definitely does appear that it is there to guide the round into the chamber.
We may be talking about two different tabs. The tab / protrusion on .40 caliber magazines is flat stainless steel and sticks out of the left side of the follower to engage the slide lock when the magazine becomes empty.

On the 9mm follower the protrusion is round, rather than flat but serves the same function.

So far as I can tell, it will never touch the bullet or cartridge.

I'm not sure I would recommend following my example, but I keep the shape the same as the original and just remove enough metal to keep it from dragging on the magazine tube. Polishing the end seems to help as much as increasing the clearance since it's hard to get any clearance and still have the slide lock work, in my experience. YMMV

Although jeffe007 is convinced he has solved the problem for his CM9, I am less confident for my guns. It seems like anything that slows the follower down on its upward travel can cause some kind of a feeding problem.

So, I hope you will forgive me if I don't give specific dimensions and do not claim to have cured the problem for sure. It could be individual pistol specific. I have two PM40 pistols and it seems like any time I change ammo brands or bullet shapes or weights they develop a feeding malady. I have one, count them one (1), brand and type of JHP ammo that is 100% reliable in both guns. :confused:

This is not a complaint, just an explanation of my reluctance to say I have solved all the issues.

[JBarbaresi]

We may be talking about two different tabs. The tab / protrusion on .40 caliber magazines is flat stainless steel and sticks out of the left side of the follower to engage the slide lock when the magazine becomes empty.

On the 9mm follower the protrusion is round, rather than flat but serves the same function.

So far as I can tell, it will never touch the bullet or cartridge.

I'm not sure I would recommend following my example, but I keep the shape the same as the original and just remove enough metal to keep it from dragging on the magazine tube. Polishing the end seems to help as much as increasing the clearance since it's hard to get any clearance and still have the slide lock work, in my experience. YMMV

Although jeffe007 is convinced he has solved the problem for his CM9, I am less confident for my guns. It seems like anything that slows the follower down on its upward travel can cause some kind of a feeding problem.

So, I hope you will forgive me if I don't give specific dimensions and do not claim to have cured the problem for sure. It could be individual pistol specific. I have two PM40 pistols and it seems like any time I change ammo brands or bullet shapes or weights they develop a feeding malady. I have one, count them one (1), brand and type of JHP ammo that is 100% reliable in both guns. :confused:

This is not a complaint, just an explanation of my reluctance to say I have solved all the issues.

i appreciate your response and information about the followers. i could see how the friction would slow the advancement of the next round and create a nosedive. i had a similar problem with my glock 32 but the tabs were molded into the inside of the magazine shell instead of on the follower.

i don't think the OP was talking about sanding the follower or magazines though. if you look on the inside of the slide release there is a tab (the part of the slide release pin that actually fits into the slide groove and locks it). i believe that is what he filed/sanded down because it was directing the rounds downward into the feed ramp. i may have read his post wrong though.

[TucsonMTB]

Wow, my reading comprehension must be low today, sorry.

You read him correctly, I believe . . . after re-reading his posting. :o

I must confess that I also polished that same area of the slide stop when it seemed to be shaving little bits of copper jacket material off of incoming rounds. I stopped removing material when copper residue stopped appearing on the slide stop and the bits of jacket material stopped showing up inside the pistol. I may not have removed enough material to eliminate nose diving because subsequent modifications to the magazine followers were also necessary.

Now, I hope you will excuse me while I go find my copy of Reading with Richard and Jane.

http://www.rarebookschool.org/2005/exhibitions/images/dickandjane/airplane2x.jpg

[JBarbaresi]

Now, I hope you will excuse me while I go find my copy of Reading with Richard and Jane.

http://www.rarebookschool.org/2005/exhibitions/images/dickandjane/airplane2x.jpg

lol

[jeffe007]

you guys at the end got it right. most definetely. also try and use rounds that have shorter OAL than majority of rounds as they will have less chance of getting stuck in the breach area. our pisto,s are just too small!;)

[hoghunter]

Out of curiosity, are there a few rounds out there that are known to have a shorter OAL than others? Conversely, are there any that are known to be longer OAL?
Thanks

[JBarbaresi]

Out of curiosity, are there a few rounds out there that are known to have a shorter OAL than others? Conversely, are there any that are known to be longer OAL?
Thanks

i don't currently have any 115gr rounds to compare side by side to, but every 147gr round i have ever fired has a flat nose. i would assume they are shorter than the dome shaped 115 and 124gr bullets. again i'm not 100% sure because i've never really focused on it before, but i would assume there is not a huge difference from brand to brand of equal weight.

[RogerP9fan]

Don't worry Tucson, it happens to the best of us. lol
OP: Great posting and congrats on a good fix.

[TucsonMTB]

Thanks, Roger! :D

[Popeye]

Here's a little test I'd like you all to try. Insert a full mag in the pistol. Point in a save direction. Now slingshot the slide or you can also trip the slide using the slide release lever. Now you should have a round in the chamber. Ok, Now drop the mag. and notice the second round in the mag has more than likely moved foward in the mag, if you rack the slide again you will notice the third round in the mag has moved foward also, but not nearly as far as the second round did. Repeat again and you'll notice the fourth has not moved at all. Now here is what I think might be the issue. The second round moved so far foward and just might be catching the release side of the slide look lever causing the round to either setting off the slide lock lever prematurely or nose diving the rounds do to the way the Kahr follower is designed. This is my belief is why we hear so many times that it's the second or possibly the third that nosedives or sets off the slide release. Slightly larger rounds in conjunction with the rounds moving foward a bit in my way of thinking could very well the colprit as to either or problem. I could very well be wrong because I'm not a gunsmith, nor do I play one on the net, but just a thought I thought I'd share with you all to see what you thought.

[TucsonMTB]

Yes, the movement you described happens while hand cycling a PM40 as well. The movement is so pronounced and interference so great that one wonders how the gun could ever work. :eek:

I tried a short action 1911 as well. There is much less movement . . . certainly, not enough to cause the bullet to crash into anything while feeding.

During actual firing, the higher action speeds may prevent so much movement. I hope so, but won't be able to test until getting to the range.

Edited to add: Just performed that same exercise using the slide lock to achieve higher slide speeds. The top round hardly moved at all. It seems like my casual overhand racking caused the gross movement observed earlier. Whew! :o

[jocko]

I thnk every kahr does what popeye is referring to. andI also think for the kahr and the design of the magazines that, that is normal for that next round tomove forward If all things are working as they should that round should still not hit the inside of the slide stop lever.. Just my 2 cents worth on that..

[Seven High]

I have noticed that when I put the six round magazine into the CM9 the top of the magazine is pushed forward a small amount by something inside the magazine well. I wonder if this action has something to do with the occasional failure to feed.

[jocko]

IMO I doubt it..

[mr surveyor]

....Now, I hope you will excuse me while I go find my copy of Reading with Richard and Jane.

http://www.rarebookschool.org/2005/exhibitions/images/dickandjane/airplane2x.jpg



wow, does that ever bring back memories. Up, up, up was one of the classics. I'm still waiting for the movie and sequals.

[jocko]

u need some serious help my friend!!

[TucsonMTB]

Surv is from Texas. Their education system is . . . uhm, different. :behindsofa:

That said, he is definitely one of the good guys who appears to have escaped their school system's attempts to spread unscientific nonsense.

[jeffe007]

yeah jocko is right. it seems that kahr designed the mags to feed whereby the cartridge after the one that feeds into the breech, does point upward and slides forward. In fact, my walther PPS did this exact same thing. so i dont think its a problem at all as that pistol was a dream to shoot feed wise-it never misfed.

Now im sure that the problem is that one must sand the part i described and the mag has a problem. when that rnd slides forward, it cants downward and sticks in that position. then it continues forward and then hits the protrusion on the slide stop. The cartridge then travels forward and hits the ramp and sticks head on.

The easy fix is to sand everything really really smooth and then use well rrounded cartridges like Pow 'r ball ammo etc. They seem to feed really well. The issue tho is when the cartridge slides forward and cant downward, it sticks in that position which causes it to go straight toward the lower pt of the feed ramp. that what causes it to jam. instead of the cartridge cant downward it should cant upward so that it can feed and be guided in to the feed ramp.

[jeffe007]

i think after about 500-1000 rnds and some more work, it should be a sweet little pocket pistol. we/ll see........

[jeffe007]

i just took pics with the only camera i have right now-my iphone 3gs camera. should give yall an idea of what im referring to here. any way,,,,,,how do i post a pic? dont tell me i gotta sign up at some lame picture sight? i hate those things......

[MW surveyor]

OK, we won't tell you you've got to sign onto one of those lame picture sites.....

But if you want to post a picture, it's the best way. Just go to photobucket and follow the instructions. BWAAHAHA.

[stumprat]

If you took the picture with your Iphone. Sign up with the tapatalk app. And you can post a pic. Directly from your camera roll.

[srg914]

I can now slingshot my CM9 with any round and no issues. The culprit was the hold-open device thats attached to the slide stop. If one holds the slide open and looks down into the breach from above, one can see it sticking out into the pathway of the projectile from the left side of the slide. Not sure what to call it but it is definetely attached to the slide's hold open.

I noticed that it was intruding into the projectiles pathway and the first movement it caused when contact was made was, to push the bullet down. Upon the bullet's continuing pathway into the barrel breach, it's trajectory moved a 2nd time. This time it moved to the right just enough to make contact, head-on, with the right side of the feed ramp.

So, w/ 600 grit sand paper and finishing w/ 1500 grit paper, i slowly sanded that little protrusion and voila! now, i have zero feed issues! its great!! i think this protrusion is some sort of guide but it seems to be too big. anyway, its a FWIW sorta thing.....

I took my new cm9 to the range yesterday and had some nosediving with wwb and was much worse with Hornady critical defense. I read your post and looking inside the breech and sure enough, the slide release pin is almost blocking the left side of the feed ramp. I don't trust myself to file it down and may have my local gunsmith do it rather than send back to Kahr and wait who knows how long. Thanks for this find. Any fix for needing to depress the mag release so deep to extract a mag? My thumb is sore from needing to press the mag release so hard. Thanks.