Recoil spring differences in K40 between old spring and new spring

[MrToad]

I recently picked up a new recoil spring for my K40, and my first thought was "hm, look at that compression", but noticed that the old spring wasn't really much more compressed based on distance between each coil...I checked and discovered the new spring had 2 more coils than the previous version. Also, when I pull the trigger back all the way the slide moves up a hair, which it did not do with the older spring. My pistol is the older version, dating from around '98 or so.


Is this normal? Was there an "improvement" made to the recoil spring to address an issue?

[Bawanna]

We've been discussing this same issue on PM9's in another thread. Your new spring has 2 more coils than your old one. I doubt if you'll be able to lock your slide back with out removing at least one and maybe 2 coils.

Try it and see if it does allow you to lock back.

If not I'd send that picture to Kahr and see what they say about this one. I did'nt now there was an old style and new style in the steel guns but apparently so perhaps.

They will most likely just send you a new spring or tell you to cut coils off. I would not cut coils until they tell you to do so and don't feel you should have to but it will work and save you the time and money of waiting etc.

[jocko]

I didn't know they did either, but I think I would try that new spring first befrore doing any cutting. If the slide will lock back, then don't cut anything but fur sure test it out to see if it is OK.

PS: I went and chekced out my two spare recoil springs that I bought from wolffs for my K9, which uses the same springs as the K40. Factory power is 20#. I had the 22#springs and it only has 19 coils like your shorter version. I am sure the 20# factory is aqlso 19 coils also. It is confusing that they sent you a longer spring, I think I would call kahr and inquire also,butI think your shorter version is the correct length. If in doubt buy thejm from wolffs and being your gun is a 40 cal, I definitely would gtet the 22 or 23# srpings. Sure would help felt recoil, and I would doubt if you would have any racking issues with only 3# more in strength.

I have always questioned why the K9 and the K40 use the same factory 20# springs when the 40 cal is just so much more powerful..

[MrToad]

I can lock the slide back, but given that the "old" spring apparently isn't compressed much more, if at all, I'm going to take your advice and contact Kahr for clarification.

[MikeyKahr]

Breathing exercises

Hi MrToad, thank you for posting your question, and thank you especially for your picture. I would heed Bawanna45cal advice completely. Try it to see if you get lockback, send pic to Kahr and ask how to proceed, wait for response. Please let us know what they say in response and ask again if you have any questions, there are many here who can help.

Now, I need to go find a yoga class quick.

[MrToad]

All righty then. I've contacted Kahr and according to their gunsmiths, the extra coils are to compensate for the newer K40 slides, which are apparently slightly longer than the older K40 slides such as mine. I presume if the slide has a dimple near the striker it is part of the newer, longer breed.

FYI, Kahr suggested clipping 1/2 a coil at a time if the slide lock does not work.

[jocko]

not so. mine has the dimple and it has the shorter spring. To my knowledge the only reasn the dimple is on the slide is to designate that you have the older style dovetail, I again just doubt their statement. The slide deminsions have not changed. Try the longer spring,if it works, just leave it alone, if not go to wolffs and just order one there and u will be good to go. again, I just don't buy their answer to just clip coils until it works. that to me is not the way to do business. My thoughts are that kahr has just went to a longer recoil spirng in their K series guns. Hell who knows anymore u ask them a question twice and you get two totally different answers..

Personally if the longer spring in the K40 works perfect,then don;'t cut it back. Quitre possably, you could have been sent the T40 recoil spring by mistake.. as the T40 slide is 1/2"longer than the K40.

[MrToad]

That's fair the dimple may be just the sight indicator difference; casual glancing of the site gave me the impression that there may have been other differences between slide types. So, I certainly could've been mistaken.

Having said all that, why would there be a noticeable difference between the spring types, assuming it is the correct part? Would that change the strength of recoil or address some magazine ejection/loading issue? I'll defer to the more knowledgeable here...

That's an interesting observation about the T40...I may just inquire with Kahr about that possibility.

[eastenn]

MrToad I ordered a new recoil spring for my K40 from Wolff and received it about 2 weeks ago. I did notice it was longer than the one that came out but I didn't think much of it therefore I didn't count the difference in coils. I put it in my K40 and while I haven't shot it, I don't have any reason to believe it won't function fine because the slide locks back easier than it did with the spring that was replaced. The spring I replaced must have got bound up somehow inside (probably put in wrong by previous owner) because one of the coils was much larger and stretched than the rest of the coils which made it really hard for me to lock the slide back. It was really hard actually, but I thought after reading all the talk on the forum about the slides being hard to lock back that it was normal. I then ordered a new spring anyway just to see and now it locks back just like all other semi-autos I have handled. BTW, mine is also an older model K40. While I don't know the build date, it does have the Hogue grips on it.

[pappy42]

MrToad I ordered a new recoil spring for my K40 from Wolff and received it about 2 weeks ago. I did notice it was longer than the one that came out but I didn't think much of it therefore I didn't count the difference in coils. I put it in my K40 and while I haven't shot it, I don't have any reason to believe it won't function fine because the slide locks back easier than it did with the spring that was replaced. The spring I replaced must have got bound up somehow inside (probably put in wrong by previous owner) because one of the coils was much larger and stretched than the rest of the coils which made it really hard for me to lock the slide back. It was really hard actually, but I thought after reading all the talk on the forum about the slides being hard to lock back that it was normal. I then ordered a new spring anyway just to see and now it locks back just like all other semi-autos I have handled. BTW, mine is also an older model K40. While I don't know the build date, it does have the Hogue grips on it.

I would suggest that you test fire your pistol after any change; prior to carrying for self defense.

[jocko]

it could have been longer as the one in the gun would have taken a set but did you count the coils to see if there was a difference there. They might have lengthened the recoil spring for some reason or other.

I certainly am not saying the longer spring is not the right one as if kahr made an in house change then it will fit. Certainly if you have the original factory one and it is shorter, then it will fit also.

If the longer one works perfect, then just put all this aside and forget about it, kahr reserves the right to make mod changes as they deem fit

[Indigo]

I have a P9 and K9 both built in 2009 one has the shorter spring and one the longer one so I'm not convinced that it isn't random. They may be switching from one kind to another and in the meantime they just grab a spring and stick it in until they run out of whichever is the old one. They still shoot fine both ways.

[jocko]

good questions

That's fair the dimple may be just the sight indicator difference; casual glancing of the site gave me the impression that there may have been other differences between slide types. So, I certainly could've been mistaken.

Having said all that, why would there be a noticeable difference between the spring types, assuming it is the correct part? Would that change the strength of recoil or address some magazine ejection/loading issue? I'll defer to the more knowledgeable here...

That's an interesting observation about the T40...I may just inquire with Kahr about that possibility.

being the k series were never a problematic gun, ur questions are good ones. If the recoil spring poundage stays the same as the original, I would say nothing has changed, quite possably kahr has increased the recoil spring poundage, as we really don'tknow from kahr really wharttheir recoil spring poudages really are. All we hav e to go by is what wolffs puts out as factory poundage on kahr springs that they make. If I owned a K40 I would certainly have the 22 or 23# over the 20#. jUST MY 2 CENTS, But again, if it ain't broke don't fix it, if it works with the longer springs, ,then just shoot it like stole it..

[jocko]

kahr has told me in the past the p9 and K9 take different recoil spirngs. I'm not sure they know sometimes, It should not be a random thing

TheP9 and K9 are different in barrel length and over all length.I would think there should be a difference in recoil springs.

U have to know to that we kahr owners of a certain model gun, tend toknow it inside and backwards, where as some of these kahr people are just employees getting a paycheck weekly, MJany may not even know what the hell they are boxing up to send out as propper parts. If a spring or springs acidentely gets in the wrong spring ben, then it is gonna get shipped out that way. Don't expect them to see the mix up, as some just don't care. I am pretty sure that when we talk to some one like Jay or \Eion, that know kahrs (I think), they are not the ones going to the parts bin and getting us the part.

[MrToad]

k I am pretty sure that when we talk to some one like Jay or \Eion, that know kahrs (I think), they are not the ones going to the parts bin and getting us the part.

Jay was the fellow I traded emails with, FWIW.