Kahr R E C O I L SPRINGS and LENGTH!

[wyntrout]

We keep seeing guys surprised that new guns with new recoil springs are longer than other (older) ones. Too many have the notion that they should be the SAME length! Here's some info from the manufacturer of Kahr springs and after-market springs for them.

Wolff makes Kahr Arms springs and sells some models with different spring rates for Kahrs:


http://www.gunsprings.com/index.cfm?page=items&cID=1&mID=29

(http://www.gunsprings.com/index.cfm?page=items&cID=1&mID=29)
From their Frequently Asked Questions:


http://www.gunsprings.com/faq

6. My spring got shorter after I used it for a short time. Is it bad?
Most new springs will take a set when they are first compressed. That means they will shorten up. This is a normal event and you should not be immediately alarmed. The greater the stress on the spring, generally the more set that will occur. All Wolff springs take this set into consideration. The ratings of the springs you receive are the ratings after the set has occurred. After set has taken place, the spring should remain essentially stable for the life of the spring.

7. My lighter [recoil] spring is longer than the heavier spring for the same gun. Is this a problem?
Wolff offers many springs in different weights for the same use. Factors such as the size of the wire, the number of coils, the outside diameter of the spring as well as the free length determine the strength of a particular spring. Often, lighter springs are longer than heavier springs because lighter wires and/or a different number of coils are used. Free length is then adjusted to achieve the exact strength desired.

8. The spring I purchased is longer than the original spring so I don't think it will fit.
The free length of a spring is not the most important factor in determining whether it will fit. Many Wolff springs are longer than factory springs. This is normal and the spring will fit.

The more important factor in determining whether a spring will fit is the number of coils in the spring times the diameter of the wire. For example, take 2 springs - one is 7 inches long and the other is 4 inches long. If both springs contain the same number of coils and use the same size wire, both springs will compress to the same solid lengths. The strengths will however be quite different but both springs will fit in the same application.


Novices with wirecutters need to determine how many coils is NORMAL for their pistol and NOT shorten springs to the size of the OLD COMPRESSED one that has taken a SET! This SET after compression is taken into consideration by the engineers and designers of the springs!


Note: I wanted to say "knuckleheads" instead of novices, but Bawanna might have chastised me.:D

I had wanted to post some pictures from the manual.pdf but wound up having to take pictures of the screen and creating jpeg pix.

I notice that the last photo for the CM/PM recoil assembly has the arrow on the wrong flange for the rear of the spring to be against! It should point at the outer sleeve flange for the outer spring.






Wynn:)

[Bongo Boy]

As an interest item, in manufacturing some springs they are pre-compressed in an effort to put in most of the permanent deformation they will experience in their expected lifetimes. This is the case where the spring itself determines the resting position of the sprung component and where that position is of interest (vehicles would be a great example). In that case, most spring 'sag' occurs in manufacturing so that very little occurs in the application.

In the case of recoil springs, the spring itself doesn't determine where the slide sits, so there would be no point in trying to 'pre-sag' the spring, really.

[jocko]

nice post wyn. would be nice if u could add this to ur newbie section

[wyntrout]

When I kludged together the newbie thing, it got too long and is passed over. I've been posting a shorter version with newcomers, so hopefully it will be viewed by more people. Though I DO tend to ramble on!:rolleyes:

Wynn:)

[JimC]

FWIW and I know for some here, it won't be worth much however, in a e-mail exchange between Eoin Pryal and myself dated 10.24.2011, Eoin stated the following when I asked about recoil assemblies and the outer spring coil count:

Our recoil asemblies now go out with the same external spring. The determining factor is the length of the recoil guide rod. If the guide rod fits and the firearm functions there is no isue. If there are failures with the firearm we will be able to go from there.

I had just received a new recoil assembly and the outer spring had 13.5 coils. I was under the impression that the new model PM9 recoil asembly had 14-15 coil count on the outer spring.

Eoin advised me the above and that the assembly that I received was correct for my newer model PM9.

My PM9 functions 100% with the 13.5 count spring.

[wyntrout]

That's what is important... reliable function... and the break-in period to wear in new close tolerances. There have been some shipping errors, though, too long or short or too powerful/weak springs for the different versions of the same pistols. Sometimes things won't work... or people think they won't work... or the springs seem too strong... depends on the user. One person's "too-hard-to-seat" spring might be a piece of cake for someone with more manual strength. I'm sure not strong, but I'm not a total wuss... yet!

Wynn:D

[jocko]

FWIW and I know for some here, it won't be worth much however, in a e-mail exchange between Eoin Pryal and myself dated 10.24.2011, Eoin stated the following when I asked about recoil assemblies and the outer spring coil count:

Our recoil asemblies now go out with the same external spring. The determining factor is the length of the recoil guide rod. If the guide rod fits and the firearm functions there is no isue. If there are failures with the firearm we will ber able to go from there.

I had just received a new recoil assembly and the outer spring had 13.5 coils. I was under the impression that the new model PM9 recoil asembly had 14-15 coil count on the outer spring.

Eoin advised me the above and that the assembly that I received was correct for my newer model PM9.

My PM9 functions 100% with the 13.5 count spring.

well that should be easy to confirm, anyonehere have a new cm9, asituses the same assembly a sthe new PM9 do. count the coils.

IMO, he is not right, but again maybe theyhave made a coil change for the new style slides to. If that would be true then IMO one cold now order from woffs their PM9 recoil spring that is even offered in two different poundages as they are of the 134 coil spring, which wold save one alot of money by not having to buy the complete recoil assembly from kahr.

someone here will soon post their outter spring count on the new style cm's.

If eion is right, then that is a big score for kahr as the 13 coil spring is alot easier to installthan the 15 coil was.

[JimC]

I going to go out on a limb here and say that I believe Eoin from Kahr CS.
I have two new recoil assemblies for my PM9 that came in the mail from Kahr only days apart due to a USPS glitch.
One from 4.24.12 and the other from 4.27.12. One has 13.5 coils and the other 13 even.
As far as I'm concerned, Eoin is correct in his statement. ;)

[Bawanna]

I think we've talked about this before. If you get the old style spring from the blunt nose version it will fit and usually work in the new style tapered slide. But the new style may or may not fit in the old style because the correct spring does have more coils.

I think this would be especially prevalent in a still new tight gun.

The older style spring in the new model would be weaker but if the guns broke in and smoothed out it would most likely work fine.

[Clark]

I have a Kahr P45 and P380.
I don't see any springs for those at Wolff.

[wyntrout]

That's right. I don't know why not. I've requested those be made available several times over the last few years. Of course, I've requested products from other companies for Kahrs, too, without success.

Wynn:)

[jocko]

I have a Kahr P45 and P380.
I don't see any springs for those at Wolff.

none yet, takes wollfs some time to get around to it, but they will eventually.