Recoil spring guide rod taking a beating

[wyntrout]

I believe that's a CW45 from a sticky here:

http://www.kahrtalk.com/showthread.p...sues-and-fixes

Most of the Kahrs need that notch. I haven't noticed any battering on my 5-year-old P380.

Here's page 2 of the above thread with an annotated picture:

http://www.kahrtalk.com/showthread.p...nd-fixes/page2

Wynn

[Redstate]

Thanks, Wynn.

[Scrambler]

K40.jpg
The recoil spring and rod move downward with the barrel during recoil, opposite the notch shown. The wear pattern looks to coincide with the distance the rod travels past the end of the spring during recoil. Wondering if the position of the end of the spring in the slide has something to do with the wear on the rod. 12 o'clock versus 6 o'clock. I put mine at 12 o'clock, closest to the front sight. Haven't had any problem. Probably wouldn't hurt to check the end of the spring and break any sharp edges. Good shooting.

[cobrasjp]

Wyn,

Are you really sure that the recoil spring assembly tilts downward with the barrel?

I always thought that the rear of the recoil spring rod rests against the frame when the pistol is assembled. Hooking it in the front side of the barrel lug is just a way of holding the recoil spring assembly in place as the gun is assembled.

[wyntrout]

The recoil rod is seated in the shelf on the underside of the barrel and moves up and down with the barrel. On most Kahrs, if the notch is not there the rod tries to make its own as I observed on my un-notched K9 from '97/'98. The polymer frame would probably deform over time if it was the support on the rear of the recoil spring assembly. The RSA provides rearward pressure to keep the barrel against the breechface of the slide.



The above picture is not mine, but another member's post, shown for a good photo of what can happen as the RSA beats against the forward RSA receptacle.

Wynn

[Exiledviking]

Did you remember to install the recoil spring with the closed end up against the guide rod flange?

Yes. It was installed correctly. Considering this new P9 has been 100% I'm functioning I'm not too worried about it. As someone pointed out it seems that the very rough ends of the recoil spring caused most of the beating. I'll keep an eye on it as I get more rounds thru it and see how it looks. I am going to look at the breech end of the guide rod to see if there's any beyond normal wear. I'm planning on picking up a K9 as the training and range gun.

[Exiledviking]

I've noticed several problems on the forum lately that make me wonder if some of the problems are for lack of the "notch" that allows the recoil assembly freedom to tilt with the barrel during firing.



The recoil spring assembly batters the rear top inside of the receptacle for the forward part of the RSA and throws the action off... also battering the RSA.

The notch can be added with a round file or careful "machining" with a Dremel or like tool.

The P380 seemed to not require one, but I noticed my 1997/1988 vintage K9 was developing fractures there and I added the notch.

There are more posts on the subject and it is ANOTHER thing to check, as with the beveling of the stripper part of the slide. The PM9 did not need the beveling, as there was plenty of room behind the top cartridge in the magazine for the "stripper" to get behind it.

Wynn

Great info. Next time I pull it apart I will check that area.

[cobrasjp]

The recoil rod is seated in the shelf on the underside of the barrel and moves up and down with the barrel.

The shelf on the underside of the barrel only holds the guide rod assembly until you put the slide assembly onto the frame. As you move the side assembly rearward, the rear head of the guide rod catches on the vertical face of the frame at the back of the recoil spring tunnel. It stays there (and the spring starts compressing) as you keep moving the slide assembly rearward until you insert the slide stop pin.

To verify this, field strip your pistol. Put the barrel on the frame with the slide stop. You should be able to cycle the barrel back and forth like it does during the firing cycle. Then insert the guide rod into the tunnel and try to seat it against the shelf on the bottom of the barrel. It can't even touch the barrel because it will come to rest against the vertical shelf at the rear of the tunnel.

Here's a couple of pictures I just took to show this. In one, the barrel is tilted way up to show the head of the guide rod resting on the frame, just as it does when the gun is assembly. It may be hard to tell, but the guide rod is as far rearward as it will go. When I tilt the barrel back down into it's normal position, it does not touch the guide rod. The other picture is with the barrel in it's normal position. If you look close you can see that the guide rod is not touching the barrel.

https://dl.dropboxusercontent.com/u/...2019.42.25.jpg


https://dl.dropboxusercontent.com/u/...2019.40.24.jpg


The video on Kahr's website with the cutaway K9 shows the guide rod and recoil spring staying parallel to the slide and not tilting with the barrel during the firing cycle. Look at about 1:06 into the video. http://www.kahr.com/patents-video.asp

Not trying to be difficult, but I don't want people to assume something about their Kahr that may not be true.

[Redstate]

Good post, cobrasjp. I tend to agree with you that the flange of the recoil rod rests against the frame. By the way, I did check my K9 (2014 model), and there is no "notch". I also did not notice any kind of wear. I only have a little over 500 rounds through it.

[wyntrout]

No problem, cobrasjp. I hadn't really looked at the action there that closely.

I got my P9 and moved the slide to the rear. The barrel tilts down at the rear and the RSA tilts up a bit at the front as well as the recoil spring is compressed... not much, but measurable ~ 1/32".

I took the slide off and put the RSA into the frame and then the barrel in place with the slide lock pin inserted partially. The guide rod flange does rest on the frame and stays about 1/8" or more forward of the barrel lug. There's a channel in the frame and the flange of the guide rod does rest against the wall at the rear of the channel.



I took some pictures:

http://s1134.photobucket.com/user/wy...%20Positioning





After reassembling the pistol I couldn't remember if it had the notch. I had to take it apart and found that there's no notch... no battering, either, so that seems okay.



Wynn