Well, the board is either fixed, or it's going to run terribly. Cross your fingers and hope for the best. I'm at my technical limit right now.

K31 help please

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Swissk31
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K31 help please

#1 Post by Swissk31 » Sun Jan 26, 2020 7:51 am

Hi folks,

I have a k31 with failure to fire issues.

Im using ppu factory ammo oal measuring 3.0005 inch.

Some (ftf) rounds are showing a light primer stikes, some no strike at all, others fire fine.

Ive stripped and cleaned the bolt inside and out and the firing pin and spring seem perfect, the rifle seems to be in excellent condition!

Any tips,tricks or solution would be greatly appreciated.
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Swissk31
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Re: K31 help please

#2 Post by Swissk31 » Sun Jan 26, 2020 7:54 am

More pics,

I beginning to think the camber is shorter than the ppu rounds as after the "click" and failure failure to fire extraction is very difficult
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72 usmc
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Re: K31 help please

#3 Post by 72 usmc » Sun Jan 26, 2020 8:09 pm

I do not have access to my original K31 ammo. It's at another location. So no factory military OAL. I have never know a k31 to not fire unless it's some BS reloads. I would get a round or two of original K31 military ammo in the small white boxes and see if the rifle fires with original ammo. This stuff.
Screen Shot 2020-01-26 at 7.28.23 PM.png
If it does you know the rifle is ok and that PPU is maybe out of spec. Now, if it still does not fire with original military factory ammo, then you got problems with the rifle.
Make sure the bolt is totally locked up . Maybe its not totally closed. On a k31 the interrupter lug on the op rod positively prevents the firing pin from touching the primer until the sleeve has rotated fully into battery. Be sure the serial number is to the top when the bolt is closed. Is your bolt fully closed? If the serial number on the bolt is not at the 12 o'clock position, the bolt is definitely not fully closed and a misfire will occur.

Are you using reloaded ammo? I see you say "factory" maybe the factory ammo is out of spec. Are you sure it's factory or some reloaded garbage put into an almost new box? see this old post:
https://www.tapatalk.com/groups/theswis ... 15593.html

A quote from the Gunny:
Are you closing the bolt all the way? If you aren't the gun will allow you to fire, but it will just close the bolt the remaining 5°. Check to make sure that when you close the bolt, there is not a tiny space ~1/16" and that the SN on the bolt is completely vertical. If it's not closed all the way and you know this and pull the trigger, you'll see the bolt close the rest of the way and it will sound like it is getting a complete strike, but it's not.
To old to fight and to old to run, a Jar head will just shoot and be done with you.

ammolab
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Re: K31 help please

#4 Post by ammolab » Sun Jan 26, 2020 8:50 pm

The bullet may be contacting the origin of rifling..makes extraction difficult and prevents full pin impact on the primer.

Check the extracted rounds for marks on the bullet ogives from the lands.

slowbob2
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Re: K31 help please

#5 Post by slowbob2 » Mon Jan 27, 2020 9:31 am

The bolt is not closing fully due to either bullet or case contact . It could be so close that just a firm thump on the bolt may fully close it . The link to the old post was an amazing collection of really bad info and advice posted by people who had no idea what they were talking about , other than Para .

Swissk31
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Re: K31 help please

#6 Post by Swissk31 » Mon Jan 27, 2020 4:20 pm

Thanks so much for all the help lads.

Oh im praying the bullet not the case is in contact. reloading isnt an option in Ireland so this has me worried 😭 ill have to hunt out gp11 ammunition

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Smokey
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Re: K31 help please

#7 Post by Smokey » Wed Jan 29, 2020 6:48 pm

GP11 has a very sharply pointed bullet with the diameter smaller than other bullets along the nose. In a newer K31 the rifling starts fairly close to the chamber to work with the bullet. The ammo you are using is probably hitting the rifling and not allowing you to close the bolt.
Arguing with someone who denounces reason is like administering medicine to a corpse.

Swissk31
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Re: K31 help please

#8 Post by Swissk31 » Thu Jan 30, 2020 1:41 pm

Thanks so much lads, ye are correct, im using new and old PPU ammo and the variation across 13 rounds was extreme.

The bullet is definitely coming in contact with the rifling first, it marred the bullet below pretty badly and very hard to extract!
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Swissk31
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Re: K31 help please

#9 Post by Swissk31 » Thu Jan 30, 2020 1:44 pm

I've 300 new stock ppu on order so ill have measure and segregate short to long 🙄

arky65
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Re: K31 help please

#10 Post by arky65 » Thu Jan 30, 2020 5:37 pm

What is the deal about reloading in Ireland?

Is it those bloody Brits?

I'd, come up with away to use a drill press or something like to seat the bullets deeper in your loaded ammo.

Swissk31
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Re: K31 help please

#11 Post by Swissk31 » Thu Jan 30, 2020 5:52 pm

Ha ha no, Ireland and the UK have a complicated past and after 38 years here i still dont fully get it.

Reloading is legal in the uk, you can reload in ireland at a registered range only. If you were caught with Primers and powder in private hands youd definitely lose your gun licences and possibly a jail spell.

Ill have to find a factory load that works 🙄

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Re: K31 help please

#12 Post by zfk55 » Thu Jan 30, 2020 6:22 pm

Go here. https://www.swissproductsusa.com/faq
Scroll down to the sixth title "what is the process for reloading the 7.5 x 55"?
This is a specific for our cartridge, and if you follow it to the letter you will no longer have any of these problems.

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Re: K31 help please

#13 Post by slowbob2 » Thu Jan 30, 2020 7:07 pm

I do not understand how the above info would help the OP ? I would say try a C-clamp , with wood jaws ? Bullet tip hole drilled .

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Re: K31 help please

#14 Post by zfk55 » Thu Jan 30, 2020 8:16 pm

Apparently you just skimmed through it.
His answer was right there in black and white.

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Re: K31 help please

#15 Post by ammolab » Thu Jan 30, 2020 9:31 pm

zfk55 wrote:
Thu Jan 30, 2020 6:22 pm
Go here. https://www.swissproductsusa.com/faq
Scroll down to the sixth title "what is the process for reloading the 7.5 x 55"?
This is a specific for our cartridge, and if you follow it to the letter you will no longer have any of these problems.
His problem is with FACTORY ammo and he has no ability to reload...
So reloading instructions help him how?

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