Walther KK500 trigger issue - not releasing firing pin

[Habhome]

I experienced some issues with my Walther KK500-M Expert rifle yesterday that had me confused and concerned.

After 11 shots the trigger suddenly stopped working. It passed the second stage and nothing happened. The firing pin seemed to be properly cocked in position ready to fire but never released.

The only adjustment I've made to the trigger from the factory default is to lower the second stage weight (F2) by one full revolution of the screw. I've shot upwards to 1000 rounds with this setting without any issues.
I cocked and uncocked the bolt several times both in the rifle and outside and it seemed to behave properly but still didn't fire when I retried.

There's only two things I can think of that might be out of the ordinary.
First I inspected the bolt and firing pin next to a team mate's and found that there is what looks like a tiny nick on the firing pin "locking heel".

Possible issue on bolt

And second we had really high humidity outside at the time (about 95%). But I believe that the rifle would not be affected by that so it's a long shot...

After about 10 minutes it suddenly started working again without me having made any changes to the rifle, bolt or trigger.
The bolt has always been stored in the case it came delivered in between uses.
Any ideas what might have caused it?

(I use the mechanical trigger and not the electronic trigger)

[Modena]

seems a few people have had trigger issues with KK500. Have a read of this, and also a further search might be useful;

http://www.targettalk.org/viewtopic.php ... 00+trigger

[Habhome]

seems a few people have had trigger issues with KK500. Have a read of this, and also a further search might be useful;

http://www.targettalk.org/viewtopic.php ... 00+trigger

Yeah I read that thread and decided to post a new topic about it since the symptoms were different so it might reveal some new issue.

Does anyone know what the factory default stage two (F2) trigger weight is? I tried a quick search but couldn't find it and haven't had the tools to measure it available. Just wondering if that (I assumed) tiny adjustment I've made could've put it really close to the lower limit of operability, and I've just been lucky it's working most of the time.

I've also reported this issue directly to the vendor I bought the rifle from as well as Walther, so I'm mostly looking for ideas of what I could do to at least ease my mind in the short term that the rifle will perform. I'm on the Swedish national team and will be competing against Denmark in just two weeks so I don't have time to send it in to be looked at by anyone right now.

I laid down at home last night with my SCATT and had no issues this time around.

[beye]

Just a few suggestions - I would use a small fine honing stone on the "nick" you found to make sure it does not have a small burr catching on the trigger sear. I would remove the trigger, clean it in naptha and blow it dry before reinstalling. Also make sure the overtravel stop is not set too close to the release point. The sear obviously did not release the firing pin.

[Habhome]

Just a few suggestions - I would use a small fine honing stone on the "nick" you found to make sure it does not have a small burr catching on the trigger sear. I would remove the trigger, clean it in naptha and blow it dry before reinstalling. Also make sure the overtravel stop is not set too close to the release point. The sear obviously did not release the firing pin.

The nick seems to be flush so there's nothing to catch on. I'm not sure I'd dare to put a honing stone against it or clean the trigger as you describe, it's just a couple of months old and I'm not yet comfortable taking it apart to that degree. There is quite a bit of overtravel so that seems doubtful that it'd be an issue. Thanks for the suggestions!

[jhmartin]

There are numerous problems associated with the KK-500 triggers and firing pins.

Get in touch with Waltherarms.com or a gunsmith who works on these.
I use Joe Hein with Elite Shooting Sports.

Replacing the trigger assy seems to be the best option.
I know a shooter on her 3rd or 4th KK-500 trigger.
My daughter had hers go out at Nationals last year ... Janet Raab from Walter replaced the trigger there and she was up and shooting the next day.

Also, I'd carry a spare firing pin ... those have been know to break the tip off.
ALWAYS use a shell or a snap cap when dry firing this rifle ... we use #4 drywall anchors ... cheap and can eject just fine

[Habhome]

There are numerous problems associated with the KK-500 triggers and firing pins.

Get in touch with Waltherarms.com or a gunsmith who works on these.
I use Joe Hein with Elite Shooting Sports.

Replacing the trigger assy seems to be the best option.
I know a shooter on her 3rd or 4th KK-500 trigger.
My daughter had hers go out at Nationals last year ... Janet Raab from Walter replaced the trigger there and she was up and shooting the next day.

Also, I'd carry a spare firing pin ... those have been know to break the tip off.
ALWAYS use a shell or a snap cap when dry firing this rifle ... we use #4 drywall anchors ... cheap and can eject just fine

I've contacted carl-walther.de since I'm in Sweden, Waltherarms.com pointed me in that direction.

We don't really have any official Walther-techs available in Sweden except at one competition per year I believe, and that's an air rifle competition.

Good idea with the firing pin, I've thought about that too. Last week a veteran had his firing pin snap right off during the Swedish Championships in his Anschütz, it wasn't his first rodeo though so he had a new one on him and just replaced it. I'll try to get my hands on one.
I always use snap caps, not once have I dry-fired without one as far as I know. I even bring them to equipment control in case they accidentally fire when checking the trigger weight.

[jhmartin]

Sorry .... I did not notice your location.
Only 2 roll pins hold in the trigger .... easy to replace.

Bolt/FP is a little more complex, but easy if you have a pin punch ... 2 pins hold all that together so take it slow the first time you take it down for cleaning .... once you do it once it's easy

[Modena]

... I even bring them to equipment control in case they accidentally fire when checking the trigger weight.

why are they checking your trigger weight at equipment control? There is no minimum trigger weight according to ISSF rules.

[Habhome]

... I even bring them to equipment control in case they accidentally fire when checking the trigger weight.

why are they checking your trigger weight at equipment control? There is no minimum trigger weight according to ISSF rules.

In the national Swedish rules there is one, and I compete both in traditional Swedish competitions and in ISSF competitions.