Problems with camming action on my L579

Discussion in 'Sako Medium Actions' started by freerange, Oct 16, 2015.

  1. freerange

    freerange Active Member

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    I recently had the above re barreled and sent back to me.
    Now the original barrel [not Sako] was put on with some slop and head space problems so i expected to have to F.L. resize my Lapua cases after the new barrel was fitted. Having done so I found that the empty case would chamber ok but would not extract unless persuaded with a leather mallet. I got back to my gunsmith who fitted my barrel and he said he noticed the lug or lugs had been gone over [an attempt at truing by a previous gunsmith] and suggested that was the reason I was having poor extraction. [I didn't notice any problems with the previous sloppy chamber however this one is a lot tighter.] He reckons he can fix it and has paid for the courier to and from his work place and the fixing of the problem he will do for free.
    As I am no way familiar with the camming action I was wondering if this is sounds about right or not?
    Maybe someone with far more knowledge than me can comment.
    Cheers

     

  2. paulsonconstruction

    paulsonconstruction Sako-addicted

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    Not sure what the "camming action" is, as I have never heard that term mentioned with regard to headspace. There is no "adjustment" of this "camming action", as headspace is determined by depth of chamber & the bolt lugs in no way have anything to do with extraction. If your brass was stretched over SAAMI spec from firing in the other barrel your FL die should have taken them back to SAAMI & they should have fit in a properly headspaced chamber. Did you try new brass? If the brass or your FL die are not the problem, then your current barrel does not have a properly headspaced chamber. Not sure I trust a smith that tells me things after the fact like, he noticed the lugs had been "gone over" (whatever that means) then sends the rifle back to you. If he thinks that may be a problem now, why didn't he take care of it when he had the rifle the first time? Did you ask him if he test fired the rifle, as that is standard practice with any rebarrel job. Sounds like he is giving you the "run around".
     
  3. 16b410

    16b410 Well-Known Member

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    You've given much to absorb and theorize on, but the only question you ask is if we have heard of 'camming action' of the bolt during lock-up. I myself have never heard the term used. The lugs turn into recesses and that is about that. Let's assume a previous 'smith ruined the lugs on the bolt in attempt at truing the action. Let's further assume the bolt is so badly ruined as a result that extraction is no longer possible, and that is a real wild assumption. What we do know is that a re-barreled rifle went back to you, the paying customer, with slop and headspace issues and regardless of who did what and when, I would be hesitant to send the rifle back there just because he reckons he can fix it. I hate criticizing someone's work, but would hate more you getting hurt with a rifle that comes back wrong. And it did come back wrong once. Please send a box of ammo to him, ask him to fire the rounds, and look closely at the spent cases he returns. This request can be presented politely as a 'peace of mind' issue.
     
  4. GreyFox

    GreyFox Well-Known Member

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    2 separate problems/conditions:
    Camming is locking up, which could be extractor "catching" inside the chamber after firing (Brass is soft - it forms to the chamber - i.e. fire forming) Chamber is not polished so the brass forms in the ridges and valleys (pits) and "sticks", Try greasing a case that has to be "malletized" or hammered out, see if the condition improves. Also, I'd remove the extractor and see how the bolt feels upon closing, of course it won't extract (no extractor) but that gives an idea of what you've got going on there.

    2nd bolt guide could be not aligning (this would be my first guess) Disassemble the bolt, and again run it in, se how it feels and how it locks up, start re-assembling the bolt and each time run it in. you're checking for fit and feel - it'll help isolate the problem.

    Of course if you have and extra bolt, you'd save slot of time but swapping them and see where the issue goes..

    just my .02 cents.
     
  5. stonecreek

    stonecreek SCC Secretary Forum Owner SCC Board Member

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    Have you checked the dimensions of your cases fired in the new chamber? You don't mention what cartridge it is chambered for, but if it is a cartridge with minimal taper then your new chamber might be too "straight" to allow normal extraction. Or, another way of putting it is that your chamber may be a tad larger in the front than in the rear. Or, it have aberrations, like an egg-shape or an annular ring, which allow the case to swell in a manner which makes it difficult to extract.

    All, or virtually all, bolt action rifles have a slight camming action as the bolt is turned. As the bolt turns down it also moves very slightly forward, which helps chamber slightly oversized cases. Conversely, as the bolt is raised the bolt moves very slightly backward, which helps extract the case. If, for any reason the case is difficult to extract then the bolt handle will typically exhibit resistance to raising it. So, is your bolt handle hard to raise after firing, or is it just difficult to pull it rearward after raising?

    Another possibility is excessive pressure. You can't necessarily use the same loads you used in your previous barrel if the chamber's dimensions, leade, groove diameter, and bore finish are somewhat different. Excessive pressure can create the same difficult extraction as a misshaped chamber.
     
  6. freerange

    freerange Active Member

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    Yeah head space has been fixed as per new barrel fitting but the camming action is the first stage of extraction provided by the bolt. I agree I should have been informed when the lugs "gone over" was first diagnosed and the reason I was told later was since I had a parkerised finish on my action then any remedial work would have entailed damaging this finish. He did test fire the rifle but with factory rounds and extraction was not an issue...yeah bugger if I know?????????
     
  7. freerange

    freerange Active Member

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    Yeah the headspace has been solved with the re-barreling but I now have a bolt not able to extract the spent cases of my F.L. resized reloaded cases unless a leather mallet is used. It will extract factory cases no problems. He has asked for 6 of my cases to be added to my rifle when I send it back to him.....
     
  8. freerange

    freerange Active Member

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    Yeah greased a couple of cases but no real difference - still hard to extricate...will try other solutions you suggest- thanks
     
  9. freerange

    freerange Active Member

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    Sorry .308 and difficult to pull rearward after raising is my problem. It ejects factory rounds ok but my previous [neck sized] cases which I have now F.L. resized and checked for length is what I am having trouble with..
     
  10. freerange

    freerange Active Member

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    Thanks guys It was an impossible question as I don't fully understand the cam assists myself. I am inclined to send it back and let him do what he has to do. I will keep you guys posted on the results...cheers
     
  11. enotstehw

    enotstehw Banned

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    Do you have a brass trimmer?
     
  12. 16b410

    16b410 Well-Known Member

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  13. 16b410

    16b410 Well-Known Member

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    Then it would seem the problem lies withing your reloads. Die issue, case too long, whatever. Load the factory cases that extracted OK as factory ammo and see what happens. I hope you sort this out...just as much as I hope to glean some insight into all the talk about 'camming action'. Always happy to learn something.
     
  14. kevinlg

    kevinlg Well-Known Member

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    I would remove the firing pin assembly, and check fore & aft closed bolt movement(with an empty chamber). Careful lifting, of the bolt handle, will reveal how much primary extraction is present.

    This will help show any changes to a proper bolt lug/receiver lug engagement.

    Then.......I'd "go" from there.....
     
  15. Ranger140892

    Ranger140892 Member

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    I know this is a super old post, but I've run into the same problem. I barreled a NIB L579 round top. As always, headspace is zero tolerance. And I'm having primary extraction issues. On close examination, I see that the extractor groove allows the case to sit at least .030" off the bolt face. That pretty much sucks up all the camming action. So by the time the bolt has rotated 90 degrees and cam'd rearward, the extractor has not pulled the case out of the chamber.

    I'll compare extractors with my other L579. If it's better, I'll order a new extractor. If they're both the same, I'll TIG fill the groove and re-machine. I'll post results.
     
  16. Ranger140892

    Ranger140892 Member

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    Well I said I'd update on the above post. The receiver is garbage. Not because of the camming action, but because of heat treating. The locking lugs are galling so badly that metal is literally crumbling off the surface. That's a Show Stopper!

    The receiver was a NIB receiver only. I ran into a lot of issues with the receiver, bottom metal, and trigger. All of it was fairly easily remedied, until I realized the heat treat was bad. It seems clear that Sako imported "seconds" receivers.

    Fortunately, I have another L579 receiver that came from a functioning rifle. Sadly, it's not a round top. The barrel fitted up nicely and was about .006" shallow on headspace. An easy reamer hand turn operation got it headspaced. We'll see how it shoots when I bed it into the stock.
     
  17. stonecreek

    stonecreek SCC Secretary Forum Owner SCC Board Member

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    I've never heard of anyone running into a problem like this with a Sako action -- even one made for a proprietary marketer like the round top you have. But Sakos are made by humans, so a foul-up is always a possibility. I take it from your description that it is the bolt lugs and not necessarily the receiver which is soft? If that is the case then the receiver could be useful with a new bolt.
     
  18. paulsonconstruction

    paulsonconstruction Sako-addicted

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    The bolt lugs are galling, so you assume the action is garbage??? Last time I looked the bolt lugs & the action were two different parts & examining one can't tell you anything definitive about the other. How does your experience with one rifle make it "clear that Sako imported "seconds" receivers."???
     

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