Not so happy 1st range report

[trikerbiker]

Just took my cm 40 to the range to break her in. After just 40 rounds I couldn't get the 5 rd mag to load...ta da! Just as has been posted, busted mag follower. Bummer so I kept shooting with the 7rd mag I also bought. That made it to 90 rds then that follower busted. I finished my 200 rd [actually 250] break-in still using the mags which feed but are a pain in the butt to load til you get the follower down into the case.
I bought this knowing of the possible issue but I usually don't believe ever thing I read and like to find out for myself. So as someone said in an earlier post: Why don't they fix the barrel feed ramp clearance issue at the factory as they know they have a problem? This gun is just hot off the presses so they obviously haven't. I guess I'll have them send me the followers and I'll dig up the posts on the do-it-yourself feed ramp repair rather than send the gun back. I have a number of Kahrs so I won't give up on this Cm 40 yet. safe shooting!

[dkmatthews]

Wow, I'm sorry to hear of your troubles. That really STINKS.

Follow up with Kahr's customer support & I'm sure they will do right by you.

[bigdave622]

Don't give up. Try to find my post with instructions to fix this. I've got about 800 rounds through mine and I'm hitting dead center on FBI milk bottle targets at 25 ft. The gun will loosen up and you need to get used to the trigger.

[TucsonMTB]

Yeah, you can do it yourself. I did, to both of my PM40's and it nicely resolved the problem. But, should you?

Maybe if I had sent both of mine in, Kahr would have gotten the hint and eliminated the problem during production by now.

In other words, by being "nice guys" rather than holding Kahr's feet to the fire, we are making it easier for them to continue to ignore the issue?

I dunno . . .

[muggsy]

It sure would be nice if someone posted a picture of a broker PM40 follower, so that one of us could determine what's causing them to break. Perhaps it time for Kahr to start to manufacture MIM followers to cure the problem.

[LorenzoB]

MIM would probably be out of the question because of quantities and mold cost. Either way, if something is actually hitting something, then it wouldn't be good for the gun with either material.

Back in March we had this thread.
http://www.kahrtalk.com/showthread.php?t=17895

There are some photos there. It would be nice to figure out the real root cause of this issue. We need more photos and better photos of more breaks. Too many happen, but hardly any photos are posted.

[LorenzoB]

Yeah, you can do it yourself. I did, to both of my PM40's and it nicely resolved the problem. But, should you?

Maybe if I had sent both of mine in, Kahr would have gotten the hint and eliminated the problem during production by now.

In other words, by being "nice guys" rather than holding Kahr's feet to the fire, we are making it easier for them to continue to ignore the issue?

I dunno . . .

This is a very good point. At our company we made a product that had a TIG weld on it. We would get a call on occasion that the weld broke. We would take care of the customer. Eventually I redesigned the product with no welds. Years later, come to find out, many people were paying their local welder to fix it and therefore we never knew how extensive the issue was! It would have been higher priority if we had known the breaks were happening more often!

[wyntrout]

I looked at some of the pictures of the magazine catch and that particular one had protrusions below the bearing ledge that were scratching the tube and the follower. Without touching the bearing ledge, those protrusions could be filed, stoned, or ground down. I had to do that with my first P380... scallop the whole protrusion without affecting the bearing ledge or lip the holds the mag in place.

I don't doubt that the .40 feed ramps are perhaps banging the followers, too. I don't understand why the front of the tube needs such a deep or low cut. The bottom of the follower's skirt seem to catch that lip a bit, too.:confused:

Wynn:)

[TucsonMTB]

The root cause for both of my PM40's was the end of the feed ramp hitting the front skirt of the follower, probably when the last round was fired. Removing a few thousandths of an inch of material from the end of the ramp itself to provide clearance between the ramp and the followers cured the problem completely for me many months ago.

Prior to removing the metal, while checking for clearance with a piece of paper as a feeler gauge, I broke more than half a dozen followers. All were cheerfully replaced by spares Kahr shipped me.

The root cause is clear. Pictures of the broken followers don't tell you much because the plastic breaks without the smooth surface of the end of the ramp leaving any marks. Basically the entire front skirt breaks off where it is attached to the follower, leaving the complete broken skirt inside the magazine when it happens. If I have a few minutes latter today, I will post a picture of the small pile of broken followers I collected, prior to modifying the ramp.

Fixing the issue at Kahr will require fitting the barrel ramps during assembly, much as they fit the barrel hoods to account for individual part variances. That's not difficult, but it adds a step the assembly process that requires time they may not be willing to spend.

[bigdave622]

It's poor engineering on Kahr's part. CAD drawings check for interferences and if there is a tolerance buildup there needs to be an drawing revision. They should also "cherry pick" guns off the assembly line to spot check. It doesn't take long to check this interference.

[hardluk1]

Send it back to have the feed ramp trimmed back a bit or grab a dremel and do it your self. The feed ramp is hitting the follower after the last round loads breaking the follower. They will make it right if you ask them to and yea,yea I should not happen but something does with all companies. Now contact them , get a shipping label and deal with it. You will be pleased when all is well with it.

[jocko]

my 21 cents. If ur busiting followers, then contactkahr andthey will pick up the gun and get it backtoyou pronto.. Don't fokk up ur warranty buy doing it yourself. It can be done but again, let kahr do this mod..

Whathardluk1 says is exactly thething to do.

contactkahr by email: attn/ Jay.

[trikerbiker]

Already sent Kahr service an email about my issue. I'm sure they will get a reply to me when they get back to work Monday. I've always had good luck in the past with their service department when I needed it. I'll keep you posted. safe shooting.

[CJB]

I don't know how much material they routinely remove, but anything taken off the barrel hood moves the end of the ramp closer to the follower.



No it doesn't. The ramp hits the follower under recoil. The hood is not even close to the breach face at that point, and any amount its been shortened is not even a factor.

Shortening the hood has a direct effect on chamber length, which makes headspace variable. Fortunately, headspace is not critical, firing pin protrusion is adequate, and manufacturing tolerances are tight enough to make hood length an almost unheard of issue. When hood length is very short, a problem does arise with the barrel's upper locking surface getting bashed up badly... which tends to make the matter even worse. What happens in that case, is that the slide moves in relation to the barrel, from thrust by the cartridge case upon the face of the slide. Upon firing, the slide will tend to move until the locking surface makes contact. Normally there is a very small forward/rear play in a barrel, just enough to allow the barrel to fit in the slide, and maybe just a bit...very little bit... more. With only a little space, the speed at which the parts contact remains low, but as the free space increases.... the parts move more, have time to build up speed... and you get metal deformation.

Hope that clarifies a bit.

[hardluk1]

Grow up children. Quit the fighting. By now most of use know the real problem even if it does not come out correctly ever time.

[yqtszhj]

Send it back to have the feed ramp trimmed back a bit or grab a dremel and do it your self.

:eek:

Not for a novice. Or as Jocko woud say "youll fokkit up andthen ur screwed"

[JERRY]

to answer the OP's question as to why this is not properly fitted at the factory before shipment is because they've probably figured it to be cheaper to fix them on warranty than to retool/recalibrate their machines for the fix the first time.

if one in five are messed up they probably fix them individual cheaper than redoing everything at the factory.

[Popeye]

I'd send that gun back as many times as it took for them to get it right. That's total Bull Shirt that you should have to do anything to that gun. It's there fault now make them fix it. Why the hell should you be paying that much money for a pistol that you feel you need to fix to make it work properly. Then if something else goes wrong with it later on, and you do have to send it back they turn all your best efforts to fix there screw up around on you and say you smithed your own pistol so your warranty is null and void. That fix it yourself scenario puts you in a no win situation for as long as you own that pistol..

[jqunac]

Agreed, don't fix it send it in but you don't have to make them do it they will fix it willfully by simply asking. My experience.

[CJB]

So, you are saying, in effect, there is no obvious excuse for Kahr allowing the ramp to hit the follower?


Pretty much. The only thing I can think of is that even if the ramp does not touch the follower under a static test, it may under recoil as the polymer frame flexes - and it does flex. So... they may have to have a greater clearance than what would might think (or they might think), to account for frame flexing, heat etc etc.

[jocko]

I would think that wold be even more evident in the kahr 40's to. that is one hell of an explosion when the 40 cal goes off, compared tothe 9, certainly not all things stayt equal when that happens.

[trikerbiker]

As I stated earlier, I wasn't worried about Kahrs warranty. Got my email first thing this morning from Jay in service with a Fed ex return label both ways. Great service, another reason I love my Kahrs, even when they have a few hick ups. Safe shooting!

[LorenzoB]

I would think that wold be even more evident in the kahr 40's to. that is one hell of an explosion when the 40 cal goes off, compared tothe 9, certainly not all things stayt equal when that happens.

Yep. This big explosion has been part of my theory. but the other part is this... When there are 3 rounds in the magazine (in .40), the front tab of the plastic follower is right at the hole where the magazine catch sits. If the mag catch is sticking into the mag too far, it will be resting against the plastic front tab of the follower. Then you combine that with the "explosion" of a 40 cal... el-snap-o!

I think some people might actually have the feed ramp hitting causing the break, but some experience the break when there are 3 rounds in the mag, so the feed ramp is nowhere near the follower. How then do we explain the front tab breaking AND the top front of the follower breaking. I think it is two separate events. The front top of the follower probably tilts up and closer to the feed ramp after the last round when it no longer has its front tab to keep it properly in the mag tube.

This is just my theory. I am not an expert. Don't try this at home. ;)

[trikerbiker]

Just to follow up about my broken mag followers. Got gun back with only an 8 day turn around time. Repair sheet says, polish feed ramp, replace followers, test fire fine. I took the barrel out and looked at it and it has some substantial rework on the lower end of the ramp compared as to what it was. Test fire tomorrow so hopefully problem will be resolved..at least according to some of the other posts after polishing. safe shooting,:) trikerbiker