New PM40 recoil spring issue

[WMac19]

Hope the pics will load properly, I'm posting from my phone.

Hit the range with my PM9 and PM40 today. It was my 2nd outing with my new PM40. On Wednesday, I ran through a very frustrating 160 rounds. One FTF but NUMEROUS premature slide locks.

I adjusted and readjusted my grip in case I was hitting the mag release. During one sequence, it was on every round.
Then I noticed the slide not returning to battery when chambering the first round with the slide release (only way I do it, btw. Never attempted slingshot with either Kahr).

Switched from Winchester WB (100 rds) to Blazer (50 rds) and only experienced one premature slide lock with Blazer. Perfect through 10 rds of Critical Defense.

Later cleaned it and lubed it and for whatever reason, changed the orientation of the recoil spring during reassembly.

Hit the range again today and it was much better with Winchester WB (100 rds) but still some slide locks, a couple thru 50 rds of Federal AE also, then perfect thru 50 of Blazer Brass and 20 Critical Defense.

When field stripping both guns for cleaning, I discovered inconsistencies in the PM40's recoil spring. Didn't notice it the last time, don't remember looking either. Incidentally, it's only when the spring is compressed. Disassembled, it looks normal. SS PM9 also displayed for reference. Anyone ever see such a thing with a new spring? Right out of the box, I could easily tell that the PM40 was much easier to manipulate the slide. During take down, I still hafta fight a little with the PM9 to keep the notches aligned but the PM40 is easy as heck:

PM9:

http://imagizer.imageshack.us/v2/150x100q90/69/cxdn.jpg (https://imageshack.com/i/1xcxdnj)

PM40:

http://imagizer.imageshack.us/v2/150x100q90/33/0bae.jpg (https://imageshack.com/i/0x0baej)

[TucsonMTB]

Yeah, the spring in my PM40 has similar variable spacing between coils, with coils near the rear closer together than those in the front section.

Mine has over a thousand rounds of wear and has never been a problem.

Not sure what to tell you. I find it a little odd too, but I can't fault my gun's performance in any way and did not even notice it until now. :rolleyes:

Edited to add: With a new pistol, including a new Kahr, there is often a several hundred round "break in" period during which FTF (Failures To Feed) can be ignored. Once the moving part polish each other the FTF issue just magically go away . . . Until you have at least a couple hundred rounds, don't worry. Be happy. Regardless of the little bump needed to the rear of slide to get into battery.

[stoshmo]

The same thing happend with the cm 40 starter.out just.like.that.like u.went.to the range took it down and noticed it.looked like that after.another out it start to look.worse almost like the spring is tryin to uncoil itself i.called.kahr.about it told them.what it looked like and they said they would send me a new front spring have yet.to get it but ended up just getting a guid rod assembly off ebay caUse.i.new i.could get it faster went out one more time with the old spring in and it ended up one coil being bigger then the rest anx it was folding over the other. Coils so.replaced it call.kahr tell them about it.maby they will send u a spring but i.would think about replaceing it im watchin the new.one to see if it.starts doing it again

[WMac19]

Thanks guys. More alarming to me than the spacing is the fact that the spring has felt significantly softer than my PM9 right out of the box. I can't imagine they'd intend that for the PM40.
I'm hoping a new assembly will be the cure for the failures.

[WMac19]

Well, I swapped out the original with a new spring assembly and just the difference in feel is VERY noticeable. The new spring offers much greater resistance. Like I'd said, I thought it very odd that the PM40's slide was significantly easier to work than my PM9's.

Now they're about the same. Treated it like a new gun. Field stripped it, cleaned it again, lubed it up and racked the slide 300 times.

Can't wait til Monday! :-)

[DavidR]

Well, I swapped out the original with a new spring assembly and just the difference in feel is VERY noticeable. The new spring offers much greater resistance. Like I'd said, I thought it very odd that the PM40's slide was significantly easier to work than my PM9's.

Now they're about the same. Treated it like a new gun. Field stripped it, cleaned it again, lubed it up and racked the slide 300 times.

Can't wait til Monday! :-)

My money says Monday will be a good day.

[WMac19]

My money says Monday will be a good day.

Thanks David. Well, your money was good today and is always good with me. ;-)

I'm completely psyched to report that I ran a flawless 210 rounds through it today. That makes 740 rounds total in 4 range visits.

I knew for sure after chambering the very first round. The slide slammed forward with such authority, far greater than it previously had with the original spring.

I flat-out love shooting this little gun. By the end, I'd wished I brought along another box of ammo.

[jocko]

:Amflag2:
Hope the pics will load properly, I'm posting from my phone.

Hit the range with my PM9 and PM40 today. It was my 2nd outing with my new PM40. On Wednesday, I ran through a very frustrating 160 rounds. One FTF but NUMEROUS premature slide locks.

I adjusted and readjusted my grip in case I was hitting the mag release. During one sequence, it was on every round.
Then I noticed the slide not returning to battery when chambering the first round with the slide release (only way I do it, btw. Never attempted slingshot with either Kahr).

Switched from Winchester WB (100 rds) to Blazer (50 rds) and only experienced one premature slide lock with Blazer. Perfect through 10 rds of Critical Defense.

Later cleaned it and lubed it and for whatever reason, changed the orientation of the recoil spring during reassembly.

Hit the range again today and it was much better with Winchester WB (100 rds) but still some slide locks, a couple thru 50 rds of Federal AE also, then perfect thru 50 of Blazer Brass and 20 Critical Defense.

When field stripping both guns for cleaning, I discovered inconsistencies in the PM40's recoil spring. Didn't notice it the last time, don't remember looking either. Incidentally, it's only when the spring is compressed. Disassembled, it looks normal. SS PM9 also displayed for reference. Anyone ever see such a thing with a new spring? Right out of the box, I could easily tell that the PM40 was much easier to manipulate the slide. During take down, I still hafta fight a little with the PM9 to keep the notches aligned but the PM40 is easy as heck:

PM9:

http://imagizer.imageshack.us/v2/150x100q90/69/cxdn.jpg (https://imageshack.com/i/1xcxdnj)

PM40:

http://imagizer.imageshack.us/v2/150x100q90/33/0bae.jpg (https://imageshack.com/i/0x0baej)

slidelocks IMO have naddato do with recoil springs. Check ur slide lock lever on the inside to see if the rounds are hitting that lever. that will cause that issue. In the kahr tech section under the propper prpping thred it addfress this an dhow to check for it. If it is hitting, just email kahr attn: Jay and state ur case and ask if they will send u a new slide release lever.

Shoot the gun left handed a few magazines to see if that goes away to. Ur thunk on the 40 cal could behitting it upon recoil andu just don't realize i.

That little springhy could also be bent out of whack. again on the kahr tech section and I think under wyns thread of cw45 fixes he shows a super photo of how that little sporinghyt should look when it is OK.

If that springhy is ent out just enough, it can upon recoil lock the slide open. This is adjustable to. U can tweek that end tip on that spring. check this stuff out. the culprin IMO is in what I am saying, not the recoil spring

[WMac19]

Thanks Jocko. I'd read in another thread, I believe it was you making a similar recommendation to somebody else experiencing similar, so I did already check to see if there was contact with the slide release. Looks good. I'll certainly follow up on your other recs, thanks!

[100percent]

wmac
When I look at the pic of the spring in your 40, I see a distorted (bent) spring. It may be rubbing on the guide and/or barrel causing drag.

[100percent]

Take a look at the edge of your spring (along the yellow lines that I added). it wobbles
http://veloliner.com/Kapm40/pretzelspring.jpg
http://veloliner.com/kapm40/pretzelspring.jpg

[FelixD]

This is a timely thread for me. I have a CM40 that is showing the same distortion or twist on its recoil spring. The gun has about 750 rds through it and has failed to reset the sear engagement several times and suffered two light primer strikes in the last 25 rds. I started thinking it maybe a trigger bar/spring problem until this evening when I noticed that as I pulled the trigger slowly the entire slide was moving to the rear approx 1/32 inch. Wondering why the slide was moving I field stripped the gun and found the distorted spring. I am thinking that the distorted spring lightened the spring weight and allowed movement of the slide to the rear which lengthened the striker/sear engagement travel causing the light strikes, etc. Does anyone have any experience with this problem? All ideas are welcome.

[WMac19]

Hmm, interesting 100percent. I'm away for the day, have my PM40 but not the original spring. I'll check tomorrow and report back. Thanks.

[muggsy]

Firm up your wrists. Both problems can be traced to limp wristing the gun. It isn't uncommon with polymer frame pistols

[WMac19]

Take a look at the edge of your spring (along the yellow lines that I added). it wobbles


Absolutely correct, 100percent. I reinstalled the old spring assembly and the inconsistencies appear exactly as in the picture you highlighted.

Funny, when disassembling again, the spring separated into its parts. No recoil spring nut. Lol... I can't even find it now!

[FelixD]

This is a timely thread for me. I have a CM40 that is showing the same distortion or twist on its recoil spring. The gun has about 750 rds through it and has failed to reset the sear engagement several times and suffered two light primer strikes in the last 25 rds. I started thinking it maybe a trigger bar/spring problem until this evening when I noticed that as I pulled the trigger slowly the entire slide was moving to the rear approx 1/32 inch. Wondering why the slide was moving I field stripped the gun and found the distorted spring. I am thinking that the distorted spring lightened the spring weight and allowed movement of the slide to the rear which lengthened the striker/sear engagement travel causing the light strikes, etc. Does anyone have any experience with this problem? All ideas are welcome.

Kudos to Kahr customer service for the quick replacement of the recoil spring I mentioned in the post. For reference, the new spring solved both the slide movement and the sear engagement. The gun is functioning correctly again. I hope the new spring gives a longer service life. I would post photos but lack the option.

[jocko]

I will give u a sgugestion to tuffen up that cm and PM40 kahr. That gun comes with only an 18# recoil outter spirng, exactly the same as the cm and pm( models. Make sno sens etome as the 40 is a very hot ass round, u notice u enever see +P in 40 cl ammo cause it is hot already. I think the gun should have the 20.5#outter recoils spring that wolff gunsprings offers for the PM9 and PM40 on their webb site. It will drop right in and should solve for sure any of this slide not returning to full battery after 700 runds etc. It is a good spring and wolffs makes all of kahrs springs

I do not know if your cm40 has the 13 or 15 coil outter spring either but wolffs willbe 13 coil which today s what kahrs has on all their cm and pm. somekahrs earlier on had the 15 coil springs in the new beveled front nose slide models but people has so many complaintes on it tha thtye fialy just went tothe 13 coil spring ,so what ever cm40 u have that 20.5# springs from wolffs will fit perfect. Just sayin

[hardluk1]

Since wolff makes the springs for kahr maybe they have some idea of a cure or confirm a heavier spring as a fix. I thought the 9mm and the 40 used the same recoil springs in stock condition ?? Heavier spring might be the right fix with heavier and faster loads of the 40. Now racking it might be an issue.

[100percent]

My PM40
I put in Wolff springs. The outer spring was a half turn less than the stock spring. I put it in without changing the inner spring at first. As I assembled the gun the inner spring collapsed down a good 1/4", where before it was still fully extended.

I took off the nut and installed the inner spring at that point.

The kit also included a new striker spring which I installed.

My gun was having a failure to cycle which was better but continued. I had to polish the extractor to make it 100% (thks Muggsy).

The recoil is much tamed. Accuracy is still great.