K31 Help

[Enfield47]

I took my K31 out to the range today for the first time and experienced some intermittent problems with the firing pin. When I would chamber a round I always made sure the bolt was fully closed by making sure the serial numbers on top of the bolt were visible. When the problem would occur the firing pin would drop when I pulled the trigger but it would not detonante the primer. After waiting to see if there would be a hang fire I tried to pull the bolt back to eject the round but I couldn't get it out of battery. I was able to pull back the firing pin and the second firing would work fine every time and then the bolt could be moved.

Maybe one round per magazine would have this issue (sometimes two rounds). I was shooting hand loads with Winchester LRP. I have used these primers in my Enfield without any issues and most worked fine in the K31 so I don't think it was the primers causing the problem. It still wouldn't explain why the bolt seemed locked until the round was fired.

Any thoughts as to what might be happening?

[TKM]

Are you chambering the round enthusiastically or just kind of easing it in?

Are your primers fully seated?

How does it work with GP11?

[BLR81]

Have you done any work or cleaning on the bolt? When you chambered the cartridge, was there any resistance? Have you checked the nub on the charging handle/cam follower for cracks or bending?

How easily does the charging handle/cam follower slide forward when you don't try to chamber a round?

It would seem that the charging handle isn't turning the locking sleeve to disengage the locking cams. If you have to really drive the charging handle hard to chamber your reloads, you may have too little headspace causing too much pressure agains to bolt face. That would make it more difficult than usual to eject a loaded round.

Once you recock the firing pin and fire the round, you relieve the stress on the bolt face and are then able to extract the case. My Wild Azz Guess.

This wouldn't explain why the shot didn't fire initially. But, If you could have extracted the unfired round you might have found a cause for that. (primer, primer seated too deeply, worn firing pin) Just saying that you may have more than one problem.

[0321jarhead]

TKM is asking the right questions but, may I also add this? Did you remove that round and look at the primer and perhaps see a small dimple on the primer? If so, you may have thought that the bolt was fully closed. It may look like it was but, there is about 1/16"ish exposed that the bolt was not completely closed though it is locked in place. I have run into that myself. It is very common for the K31 to have that happen. You have to be very firm when closing the bolt. Sometimes we don't realize we are being a little gentle when closing it.

[rojocorsa]

Always remember to make sure that the S/N is on the top to make sure it's in battery properly.

[Mutant]

Resize the shoulder of the cases more and/or seat the bullets more. K-31 has no cam action and overlength is critical. My RCBS dies do not move the shoulders down enough and I bought Lee - OK.

[Enfield47]

Thanks for the feedback.

The primers are seated flush, not sticking out or seated too deeply. Unfortunately I can't try the GP11 ammo since it has steel in the bullet. The RSOs were constantly checking for that today with a magnet after each line break.

I didn't enthusiasticly close the bolt when loading a round, more of a push. Maybe that wasn't enough force to properly chamber the round all of the time.

The only thing I have done to the bolt was to disassemble it when I initially got it and put some oil on the firing pin spring. Everything seems pretty smooth when I open and close it with or without a round. If there was a small gap where the lugs weren't fully engaged would pulling the trigger lock the lugs and then bring the bolt face into proper alignment for the firing pin to strike the primer once I recocked it? If so, maybe that is what I was experiencing. Perhaps the recoil of firing the round also helped align everything properly so the bolt would slide back and eject the case.

A friend and I measured the chamber using the Hornady measuring device, a modified case, and the ogive of the bullet to be sure we had the proper seating depth. None of the bullets had any indentations from the lands or grooves when extracted.

I looked at the primer after it had been fired and it looked the same as the others that functioned properly. I'm hoping that if I will be a bit more firm and smack the bolt into battery this problem may go away then. It's quite a bit different feeling than my other bolt guns so I guess I need to make the adjustment on how I work it.

I did use RCBS dies so I'm going to check and see how the fire formed cases compare to the resized ones. Hopefully they aren't that different in the shoulder of the case.

[OpenSightsOnly]

Are you using new/virgin brass or once-fired brass from your rifle?

If latter, did you measure the shoulder of the once-fired brass prior to FL sizing? If you do not have the Hornady cartridge headspace tool, use a deprimed 9mm case as cartridge headspace tool. You should have at least 2 thou shoulder change after FL sizing. If you are using Prvi brass, that brass is hard so you may have an inconsistent bump. I set my FL sizing a minimum of 3 thou bump for FL sizing. Also, get a bullet comparator so that you have an idea on how deep to seat the bullet. Since that K31 has a short throat, that tool will be useful if you use different bullets since each bullet has different ogive.

I have to ask this - once you chamber a round do you check if the op rod is flush against the receiver. I use that as my index as opposed to the serial number at 12.

Thanks for the feedback.

The primers are seated flush, not sticking out or seated too deeply. Unfortunately I can't try the GP11 ammo since it has steel in the bullet. The RSOs were constantly checking for that today with a magnet after each line break.

I didn't enthusiasticly close the bolt when loading a round, more of a push. Maybe that wasn't enough force to properly chamber the round all of the time.

The only thing I have done to the bolt was to disassemble it when I initially got it and put some oil on the firing pin spring. Everything seems pretty smooth when I open and close it with or without a round. If there was a small gap where the lugs weren't fully engaged would pulling the trigger lock the lugs and then bring the bolt face into proper alignment for the firing pin to strike the primer once I recocked it? If so, maybe that is what I was experiencing. Perhaps the recoil of firing the round also helped align everything properly so the bolt would slide back and eject the case.

A friend and I measured the chamber using the Hornady measuring device, a modified case, and the ogive of the bullet to be sure we had the proper seating depth. None of the bullets had any indentations from the lands or grooves when extracted.

I looked at the primer after it had been fired and it looked the same as the others that functioned properly. I'm hoping that if I will be a bit more firm and smack the bolt into battery this problem may go away then. It's quite a bit different feeling than my other bolt guns so I guess I need to make the adjustment on how I work it.

I did use RCBS dies so I'm going to check and see how the fire formed cases compare to the resized ones. Hopefully they aren't that different in the shoulder of the case.

[Guisan]

There should be no oil or grease inside a Swiss straight-pull bolt durings use, a little grease at the spot where the bolt cam follower enters the bolt sleeve is recommended to make it operate more smooth.
For storage protective grease is ok.

[BLR81]

Thanks for the feedback.

The primers are seated flush, not sticking out or seated too deeply. Unfortunately I can't try the GP11 ammo since it has steel in the bullet. The RSOs were constantly checking for that today with a magnet after each line break.

I didn't enthusiasticly close the bolt when loading a round, more of a push. Maybe that wasn't enough force to properly chamber the round all of the time.

The only thing I have done to the bolt was to disassemble it when I initially got it and put some oil on the firing pin spring. Everything seems pretty smooth when I open and close it with or without a round. If there was a small gap where the lugs weren't fully engaged would pulling the trigger lock the lugs and then bring the bolt face into proper alignment for the firing pin to strike the primer once I recocked it? If so, maybe that is what I was experiencing. Perhaps the recoil of firing the round also helped align everything properly so the bolt would slide back and eject the case.

A friend and I measured the chamber using the Hornady measuring device, a modified case, and the ogive of the bullet to be sure we had the proper seating depth. None of the bullets had any indentations from the lands or grooves when extracted.

I looked at the primer after it had been fired and it looked the same as the others that functioned properly. I'm hoping that if I will be a bit more firm and smack the bolt into battery this problem may go away then. It's quite a bit different feeling than my other bolt guns so I guess I need to make the adjustment on how I work it.

I did use RCBS dies so I'm going to check and see how the fire formed cases compare to the resized ones. Hopefully they aren't that different in the shoulder of the case.

First off listen to Guisan and remove all the grease from inside and outside the bolts. You may place a little (LITTLE) grease on the cocking handle side of the locking lugs.

No, firing or recocking will not cause the bolt to go into battery. Your firing problem is more than likely NOT related to the fact that you can't unload a chambered round.

If "enthusiasticly" means that it required some effort to close the bolt, do go back and compare the fired and sized cases for proper shoulder measurement. Also, even tho you may not be able to fire the GP11 bullets, there is no reason why you can't measure them as a reference to set you resizing die for proper head space.

Finally, if you as you said "I'm hoping that if I will be a bit more firm and smack the bolt into battery this problem may go away then." it could possibly go away. Forcing the charging handle to close the bolt on a cartridge that is not head spaced properly can break off the tab on the charging handle that rotates the bolt. In which case, the bolt will not lock, the rifle will fire, and the bolt will come flying back and hit you in the face.

Please never force a Swiss rifle into battery. If the cartridge is loaded and head spaced properly, it should close as easy as it does with no cartridge in the mag and the rifle in SAFE.

[Mutant]

Don't measure like a real reloader, just try two or three with shortned shoulders and deeper bullets. It works with my 6 Swiss rifles. Nothing fancy or technical. Just go shorter, try them in the rifle, and say "dang gummit, dat der boolit slipped in the chamber like young Peggy Sue and ..cough, cough, cough.........."

[CSACANNONEER]

Your shoulders need to be set back a little. The gun is not going into battery. Also, primers should never be flush. They should be set about .002" deeper than flush.

[Latigo]

FULL length size, trim to length, do NOT "smack that bolt into battery".

Please read here..... http://www.calguns.net/calgunforum/s...d.php?t=528460 Posts #1 and #7.
Follow that and the problem will disappear. The likelihood of something being wrong with your rifle is minimal.

Please post results.

[Enfield47]

When I measured the chamber with the Hornady device I used a GP11 case that was made into a modified case to determine the seating depth.

The rounds all fed smoothly, even the ones that needed the cocking handle to be reset and no excess force was applied to the bolt to close it.

The bolt slides with very little resistance for feeding and ejecting. In looking at a few videos of how people close the bolt on the K31, I was doing it more gently than they were. I was closing it more like I do on my Enfield which has no resistance. Maybe that was causing it to not fully close and leave a small gap where the firing pin couldn't contact the primer. I need to take it out again soon to test that theory.

I will disassemble the bolt and wipe down the firing pin spring that I put a little oil on. Other than a little grease on the bolt cam follower the bolt was left alone and no other areas of the bolt assembly were oiled or greased.

I really like the rifle and it was fun to shoot so I want to get everything working properly.

I am using new Prvi brass for my handloads.

[Justintoxicated]

When I measured the chamber with the Hornady device I used a GP11 case that was made into a modified case to determine the seating depth.

The rounds all fed smoothly, even the ones that needed the cocking handle to be reset and no excess force was applied to the bolt to close it.

The bolt slides with very little resistance for feeding and ejecting. In looking at a few videos of how people close the bolt on the K31, I was doing it more gently than they were. I was closing it more like I do on my Enfield which has no resistance. Maybe that was causing it to not fully close and leave a small gap where the firing pin couldn't contact the primer. I need to take it out again soon to test that theory.

I will disassemble the bolt and wipe down the firing pin spring that I put a little oil on. Other than a little grease on the bolt cam follower the bolt was left alone and no other areas of the bolt assembly were oiled or greased.

I really like the rifle and it was fun to shoot so I want to get everything working properly.

I am using new Prvi brass for my handloads.

You should full length size the PRVI brass for the K31 using K31 specific Hornady or Redding dies only.