New PM40 recoil spring issue

[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.