PM9 nose dive, possible fix

[reade]

Hello, I'm new here and was referred to come post this here by someone on another forum.

I had a horrible problem with nose dive jams on my PM9 with both 6 and 7 round mags, worst with the 7. I understand all about the slack in between the rounds in this single stack magazine. So there's no need to try to explain that to me. What I'm posting about was the problem(s) I see with the design and my attempt at addressing them.

It's known that the rounds have quite a bit of space between them (especially 6 and 7) so the top rounds bottom rim can catch in the lower rounds groove and drag it ahead as the top round is chambered. (see edit) This can leave the lower round under the feeding ramp. If you look at the magazine there is nothing to prevent this. There is also a void in the frame in front of the magazine that allows the round to move even further ahead, when this happens it helps in creating a nose dive jam.

What I did to "fix" my problem was make a metal shim the fills that void and so it acts like the part of the magazine that doesn't exist. This keeps the round from moving too far ahead and getting stuck under the feeding ramp.

What I'm looking for a a few people who have this same problem to use as beta testers for my FTF Nose Dive shim to see if it is indeed a "fix" or not. In my case my PM9 has ran over 200 round flawlessly since being installed.

The shim is attached with 3M VHB tape and so does not require any modification to install and is 100% removable with no damage to the gun.

Understand if you try my shim and you have some unforeseen problem that damages the gun I will not be held responsible as this is a beta test. All I know is I've had great success with mine and absolutely no problem(s).

If you are interested in talking to me or learning more I can be reached by PM.

*Edit* after looking more closely at this my first impression is wrong, it's the lower round hitting the top of the magazine and it's steep angle that throws the round ahead. Anywho, what exactly causes it is not the issue, it happens on some guns and it's the pits for their owners.

[OldLincoln]

Pics?

[HDoc]

Yep, pictures or diagrams would help my spatially challenged self.

[reade]

http://img.photobucket.com/albums/v626/jakeddy/IMG_0739.jpg

[CJB]

The simplest fixes are always the most elegant. And, elegance matters.

[reade]

CJB, that's more than kind of you.

[littlemike]

I am inerested in you fix my brand new CW-9 does a nose dive jam on all most every round.

[gb6491]

I am inerested in you fix my brand new CW-9 does a nose dive jam on all most every round.
Welcome to the forums. In regards to your CW9, you might want to check that the magazine spring is installed correctly (we seen some come from the factory with the spring installed improperly): http://kahrtalk.com/showpost.php?p=105359&postcount=6
Regards,
Greg

[reade]

Greg, I assume your welcome is directed at me as well as littlemike since this is my thread so I'll say thank you.

I'm very interested in your mag follower mod as well. I wish we lived closer to each other so we could exchange notes and do some side by side testing.

[HDoc]

Not sure what I'm looking for in the photo. Where's the shim?

[reade]

The trigger bar runs right by it, there is a notch milled in the side of it for the trigger bar to clear. It is on the trigger side of the mag well. It runs from the top of the frame down to the cross piece at the mag release.

[gb6491]

Greg, I assume your welcome is directed at me as well as littlemike since this is my thread so I'll say thank you.

I'm very interested in your mag follower mod as well. I wish we lived closer to each other so we could exchange notes and do some side by side testing.
Indeed reade and to be more specific, welcome aboard!:)
http://smilearchive.com/s/contrib/edoom/spacecraft.gif


Not sure what I'm looking for in the photo. Where's the shim?


The trigger bar runs right by it, there is a notch milled in the side of it for the trigger bar to clear. It is on the trigger side of the mag well. It runs from the top of the frame down to the cross piece at the mag release.
HDoc,
reade has done an excellent job describing his interesting mod, but I've taken the liberty of putting an arrow on his photo (reade, my apologies for not asking your permission; I'll remove it if you so desire) to further highlight it.
http://i47.tinypic.com/oqzpk0.jpg
Regards,
Greg

[reade]

Greg, thank you for the help. I currently have two testers trying them out. Both are owners who have had bad luck with their guns. One has done the magazine mod to his and says he noticed no real difference, the other has spent money buying other new mags etc. even after sending his gun in for warranty work to no real avail. So if they have good results it may mean I'm onto something.

Time will tell.

[OldLincoln]

I've been feeling a bit dense studying this thread to figure out "how" the tab works. It took me a while to catch on that the barrel ramp is down when looking into an open slide, which explains the bullet being half way up the ramp. So with the slide forward and the stop pin removed I see the hollow point bullet doesn't fully hit the ramp as it sits in the mag. Your ramp extension sits under the barrel ramp filling the gap so the bullet slides onto your ramp when it noses down and is pushed up instead of lodging.

Is this about right??

Of course had the ramp about 1/4" more length it wouldn't be necessary. But then the rest of the assembly doesn't work. Makes me wonder if this is why the 1911 design used an integral frame ramp.

[reade]

You are correct sir!

[markrb]

Are you adding height in addition to going down the slot?
From looking at the way my magazines go into the frame it looks the the metal of the magazine covers almost all of the slot. It would only make sense to me if you were also adding height to that section of the frame.
Would it be possible to show a picture with a magazine inserted as well? Maybe even one with a couple of rounds in the magazine of the disassembled frame?

Thanks,
Mark

[CJB]

. Makes me wonder if this is why the 1911 design used an integral frame ramp.

As someone who's poured over the writings of JMB, read, re-re-re-read biographies - authorized or not, I think I can safely say, Browning was a man of simplicity, not extravagance, either in personal life or mechanical design.

Browning worked with what he had, and what Ed Browning could figure out how to actually build. Remember - their machine shop was very limited. It ran on overhead leather belt pulleys and such. This is a documented fact!

Browning did, on the 1911, what he was capable of doing, with the presence of mind knowing what the limitations of the current state of manufacturing more-or-less was. Ed had no schooling as a machine operator - he learned like everyone else, the hard way.

Its a wonder the 1911, or any of Browning's designs, actually saw light of day. He didn't submit prints, he submitted working (and well working at that) prototypes. The end users of the day took it from there and refined what grade school education and country boy know how wrought in steel to make happen in the light of day.

[reade]

Here's a pic of the shim in the frame and the mag installed (locked on it's release) I removed the follower so you can see the gap the shim fills.

http://img.photobucket.com/albums/v626/jakeddy/IMG_0900.jpg

The pistol assembled (again with the mag locked in place). The follower is out so you can see the transition from the mag onto the shim into the ramp.

http://img.photobucket.com/albums/v626/jakeddy/33u49cy.jpg

Every nose dive jam I personally had was from the tip of the bullet getting stuck in the gap you see filled by the shim. That gap is just under 3/16" (.160+) in height and 1/8" (.100+) deep allowing the tip of the bullet to wedge it's self in there. The shim keeps the bullet from moving any further froward than the thickness of the magazine, or about (.025 +-).

*edit* new pic with neat arrows courtesy of Greg. Thanks!!!

[reade]

Makes me wonder if this is why the 1911 design used an integral frame ramp.

That is very similar to what I am attempting to create. Or, at least as close as can be done within the dimensions and angles given.

[OldLincoln]

I see the relationship of the shim to the ramp in your second pic and it is what I expected. I do finally get what you have done and it is a great start. Essentially you are filling the gap between the mag lip and the ramp to block the nose dive.

I had the misconception that the barrel returned down before the round dived, but after playing with it see it happens early on. Now I wonder if it would work even better with the shim bent to "h" with the bottom sitting flush with the forward part of the ramp bottom.

I also wonder about the mag lip being formed to fill the gap. It doesn't make sense to me to have the mag front cut so low when the top round always sticks up. It could stand 1/4" taller and fix the dive issue right there. The top round could glide off that lip smoothly onto the barrel ramp and solve a lot of feed issues.

[LorenzoB]

Welcome reade!

Nice work and analysis.

I have a CW9 and use both the 7 and 8 round mags and have not had this issue with nosedives (yet), but it has been a concern of mine (especially since I plan on buying another Kahr or two). This is an interesting mod and you may really be on to something. I always thought the follower would be the route to take, but your idea looks good.

Thanks for posting! And since you are here at KahrTalk now, you should kick off your shoes and stay a while!

[LorenzoB]

...I also wonder about the mag lip being formed to fill the gap. It doesn't make sense to me to have the mag front cut so low when the top round always sticks up. It could stand 1/4" taller and fix the dive issue right there. The top round could glide off that lip smoothly onto the barrel ramp and solve a lot of feed issues.

I was just thinking that too!

[reade]

I see the relationship of the shim to the ramp in your second pic and it is what I expected. I do finally get what you have done and it is a great start. Essentially you are filling the gap between the mag lip and the ramp to block the nose dive.

I had the misconception that the barrel returned down before the round dived, but after playing with it see it happens early on. Now I wonder if it would work even better with the shim bent to "h" with the bottom sitting flush with the forward part of the ramp bottom.

I also wonder about the mag lip being formed to fill the gap. It doesn't make sense to me to have the mag front cut so low when the top round always sticks up. It could stand 1/4" taller and fix the dive issue right there. The top round could glide off that lip smoothly onto the barrel ramp and solve a lot of feed issues.

You understand the problem and it's solution. IMHO

[reade]

Just got home from running another 150 rounds through my PM9 with no FTF at all (or or problems).

[CJB]

I like the "fix" and its simplicity, elegance... just great.

Now for the nay side. Its very hard to prove a negative.

That is, do we know this is a "fix", or if for some other reason, we have a properly functioning pistol? Double blind testing would confirm it - that is - a well working pistol with "the fix" should remain so. And a ill working pistol should return to ill working after de-implementing "the fix".

Not trying to be negative... just thorough. If it really works - SELL it to Kahr!~

[reade]

I agree. That's why I have one on the way out to a very unhappy camper. He will test his gun as follows, run it without the shim for x amount of rounds and record his stats and then install the shim and run as many or more rounds and record.

I took a black Sharpie marker and "blued" my shim before firing today to see exactly where things did touch and there is contact on both where the mag touched on it's way in and there is making above that showing at least a few rounds touched being chambered. I took a picture but it is misleading if you don't take into consideration the magazine goes up further when being installed and then moves back down into position. The "marks" show more contact than was actually made by the bullet tip(s). I'll not post it as it might be misunderstood (to my benefit).

[jocko]

its a fix for his gun, 99% do not require it.IMO, something else is wrong with the gun but his partricular fix corrected "his" guns issue. IMO as with other products u can have an issue and the fix doesn't really override the issue but circumvents it.. But not knocking what Reade did to his gun either. If he is happy then that is all that matters...

[reade]

To amend my above post, I figured out a way to show the actual contact from rounds touching the shim while being chambered. I seated the mag (less follower) the scratches from the top of the mag to the top of the shim are from rounds. Take into consideration there is .060 of clearance between the top of the shim and the bottom of the ramp. My measurements show right at .200 from the mag to the ramp (+-), with the shim this is reduced to .060.

http://img.photobucket.com/albums/v626/jakeddy/IMG_0909.jpg


OK, it's time to let this rest until I hear from the other testers. I'll let you know what I find out when I hear from them.

[reade]

its a fix for his gun, 99% do not require it.IMO, something else is wrong with the gun but his partricular fix corrected "his" guns issue. IMO as with other products u can have an issue and the fix doesn't really override the issue but circumvents it.. But not knocking what Reade did to his gun either. If he is happy then that is all that matters...

Ultimately you are right. All I've done even if I'm 100% correct is show the possible need for a magazine that's taller in the front and then only on a certain percentage of guns. But if you happen to own one of those guns this could be a band-aid until a "better" magazine is offered. If ever.

OK, I'll stop for now until I have something to share.

[OldLincoln]

Seems like some mag company out there could raise the front and fix the problem and patent it as an improvement over the original patent. Perhaps Kahr should get busy on this to beat them to it.

[CJB]

While I agree with Jocko (and my previous post supports my agreement), playing Devil's advocate for a second....

Kahr made changes in the slides on the PM series... slightly longer, slightly heavier (when including longer barrel as well). That also gave them just a little more room for more recoil spring. Was this change a stylistic one, or a subtle refinement to the design to make it a little less finicky? I think the latter.

That is to say, large pistols with heavy parts and plenty of overtravel on the pickup of a fresh round, have all seemed to fared better when it comes to feeding (ie, BHP, 1911, 39/59, 92, P38, etc etc). Small pistols, with lighter parts - that also move much faster - and have minimal over-travel of parts to ensure proper functioning tend to be a little picky with what ammo they shoot, and to some degree, with who they choose as a "suitable shooter" for themselves.

This very well could be a refinement that is welcome, and which takes a little bit of the "finicky" out of the PM's. They're not all finicky... Me, I tend to have a firm grip on things and get good cycling with very short 1911's and such. I know I'm not Joe Average when it comes to that sort of thing. Other folks have problems, some have problems with one ammo or another, while other shooters see the exact reverse with the very same pistol. Finicky is the word. If the shim makes that less so... just sayin'!

[jocko]

possablegood point and assumption. They certainly in lenghtening the slide and barrel etc, didn't do anything for the slide over travel to pick up a fresh round, which has been on the 45's a tad of an issue, not much to concern IMO but it has been there. It is all about timing on semi's and no doubt the bigger the gun the easier to get the timing thing under control. I am amazed to see the little komifornia P380 doing so well with loaded round indicator, and mag disconnet squeezed into this small ass gun. 10 same model guns can have 10 different quirks that more than likely can all be in house modifed to make work correctly. Those who do not want to attempt should certainy take advantage of the makers warranty. Just sayin

I certainly can't complaing about my two blunt nose PM9's. they go bang every time and do all the other things right also.. They are IMO simply the best kahrs PM9's made.

I always felt kahr did the belevled slide thing on the PM series to bring them up to looks like the rest of their line of guns. U khow these gun makers have to make some changes to keep us buying to...

My prediction down the road will be slides in camo, desert brown, all steel versions in two tone. I would think they could put that \dlc finish on kahr sin any damn color they chose. Its a fightin gun, so lets make it look like that:blah::blah: Just sayin

[ReFracture]

I have the same issue with a new CM9 I bought yesterday.

This all just seems.. crazy to me. I'm going to call Kahr and see what they tell me about my issue. I need a reliable conceal carry pistol, I bought the Kahr because it seemed of higher quality than other offerings I have seen. I really don't want to mess with modifying a new gun to make it reliable.

I understand what people are saying about how Kahr does not make the magazines, but as far as I'm concerned those are just as important to the gun as the barrel, trigger, or any other component necessary to make it function, and skimping on that is no better than skimping on anything else.

I'll let you guys know what Kahr tells me.

[Pogi]

Hi reade!

With the shim thing, what's the effect if you ride the slide?

I noticed shouldn't this thread be Kahr Teched?

[CJB]

I have the same issue with a new CM9 I bought yesterday.

You may want to try the generic and customary things - clean, lube, and shoot it for at least 200 rounds.

[CrabbyAzz]

What is the width, thickness and length of the shim. I have some of the 3M tape laying around from an auto body trim repair. Wouldn't mind giving it a try.

[ReFracture]

You may want to try the generic and customary things - clean, lube, and shoot it for at least 200 rounds.
Aye, I failed to mention that the first thing I did after I got it was cleaned all the factory grease off and then relubed it, took it to the range with 200 rounds to break it in.

I contacted Kahr by email and Jay got back to me saying the problem is with my recoil spring, he is sending me a new one.

At a point I google searched and found another thread here saying it is some sort of timing issue with the gun when another guy had the same problem.. so hopefully that's it, because I otherwise love this little gun. I'm amazed with how well I am able to group with a gun this light and small...

[jocko]

jRefracture. alot of gun companies do not make their own mags. not IMO a bad thing, they let companies who specialize in that do that stuff, to their specs, same thing with some of the barrels.

The new recoil spring would be my first suggestion to try, ass if it is timing related, that normally falls back on the recoil assembly. Becuase it isnew does not mean it is what it should be. At least u have eliminated that possability if the issue continues. stick with it, the gun will come to you..

[error404]

I'm one of the Beta testers...

My PM9 used to jamb a lot (nose-dives). After talking to Kahr, I replaced the recoil spring and bought another magazine (6 rounds/flush).

That didn't solve the problem, so I sent it back to karh

Here is the "Return to manufacturer letter" that I sent along with my PM-9


I bought this weapon (ICXXXX) brand new on Aug. 2010 and from the start, it has been given me this consistent FTF issue (even after the break-in period):
I would load the gun as per the instructions in the manual. The gun will successfully shoot the first round, but during the following rounds... one will fail to feed (randomly). The slider would be stuck half way open and I'm able to look at the chamber area. I can see the bullet (that would be next in line), facing a little bit down (nose-dive). The tip of the bullet would be hitting the feed ramp causing it to jam. The jam can be easily clear-up by tap & rack

After ±800 rounds and the issue becoming more persistent. I contacted Kahr Arms by e-mail on Oct. of 2010.
I was suggested by Jay Dandrea (Jay.dandrea@kahr.com) to replace my recoil spring. Which I did (I bought a factory replacement from http://www.kahr.com/Parts/ ).
Replacing the recoil spring help reduce the amount of FTF that I was having, but I still get them often. I have put another ±650 rounds since I change the recoil spring.

I have 3 factory magazines (two 6 round mags, and one 7 round extended mag.). The FTF happens on all the magazine, but specially on the 7 round mag.

I have try running different ammunition, but it did not solved the issue:
Winchester White Box (FMJ)
Remington (FMJ)
Blazer Brass (FMJ)
PMC (FMJ)
PPU (JHP)
Fiocchi (flat nose FMJTC)
Gold Dot (JHP)

I have let other experienced shooters shoot the weapon and they have had the same outcome (FTF).

I have clean the weapon multiple times: Sometimes being generous when oiling it, and sometimes almost dry. (So far I get the feeling the pistol likes to run with the least amount of oil).

At this point, I am out of ideas on how to solve these issues on my own and I sincerely hope that Kahr's Service Department can track the problem and turn my weapon into something that I can trust for daily carry.

Best regards,


XXXXXXXXXXXX


Kahr replaced the recoil spring again and polished the feed ramp. That helped a lot, but I still get some nose-dives once in a while (specially with the extended magazine). My gun, simply was not dependable as a carry weapon and lost interest on the gun until I read about the possible fix in another forum.

Before installing the shim, I did a some more tests:

(gun was clean and lubed with Miltec-1)

Federal 115gr RN:
22 rounds total = no ftf
(used all 3 magazines once)

PPU 147gr hollow point
22 rounds total = no ftf
(used all 3 magazines once)

147 gr Pen bullets (reloads) 2.6 bulleyes
50 rounds = I had 3 nose-dives while inserting the magazine
(because they are reloads meant for my beretta 92fs, I will not count this 3 malfunctions. Perhaps reducing the OAL could fix the problem)

http://img338.imageshack.us/img338/634/p1050999y.jpg


Winchester white box 115gr FMJ
50 rounds total = 3 nose-dives on the extended magazine

2 of the FTF were hitting below the feed ramp and one was hitting the beginning of the ramp (see picture)

http://img220.imageshack.us/img220/3944/nosedive.jpg

================================





Then I installed the shim and only cleaned the bottom half of the gun. Left the feed ramp/barrel dirty on purpose.

I shot 27 rounds of federal (no failures) and 50 rounds of Winchester white box without any trouble. I used all 3 magazines with more emphasis on the extended magazine.


I know, it's not an extended test... But I feel the shim, helped my PM-9 to resolved my FTF.

If I get another FTF (with the shim installed) I'll come back and report.