Win M70 CRF extractor tension

Discussion in 'Gunsmithing' started by Hand Skills, Sep 30, 2018.

  1. Hand Skills

    Hand Skills Well-Known Member

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    So, I'm sure this is a common issue. I've done a bit of searching, but haven't come up with anything.

    The claw extractor on a recent acquisition of mine is suffering from inadequate spring tension.

    I think the extractor ring might actually be the problem. It deforms easily and doesn't remember its shape. The extractor itself seems fine. Upon reassembly, it will reliably eject the first couple of rounds, but then loses tension and starts dropping brass on the feed rails.

    I was able to increase tension and get reliable extraction by shimming between the bolt body and leaf spring with a folded cleaning patch.

    Am I correct in assuming the extractor ring should behave like a snap ring and snap into place? If so, who makes a high quality (spring steel) replacement?

    Any tuning info would be appreciated, but if I'm on the right track, I'm wondering specifically if I should be looking for original parts or aftermarket?

    Thanks!
     
    Last edited: Sep 30, 2018
  2. MagnumManiac

    MagnumManiac Well-Known Member

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    The extractor collar has only one purpose, to apply spring pressure to the extractor so it follows the collars rotation without binding. It does not aid in ‘helping’ apply spring to the holding of cartridges, however.
    Due to the Model 70 design incorporating the anti-bind linkage, it is often difficult getting the collar square again after removal/re-assembly.
    I use shims when re-assembling 70 bolts to hold the collar square and hold the collar with specialised vise locking pliers as the extractor is slid onto the collar, then I check with a loaded round to see if the extractor holds the round as it is rotated to bolt close position. The case should stay witheld until about 90% of the rotation then should go loose and fall over. If it falls over prior to 90% rotation, you have either an alignment problem or not enough spring pressure. The case should snap under the extractor and be firm, not tight and not loose,

    Hope this helps.

    Cheers.
     
  3. Hand Skills

    Hand Skills Well-Known Member

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    Makes sense, thank you. I think I will try a new (factory) extractor ring anyway - this one has the rigidity of lead. Are the rings you have removed super soft? That's what I don't understand - how can the ring provide tension if it has no shape memory?

    I understand the principal of alignment, it seems like my ring is too big, or the diameter of the raceway is too small. Like I said, I get it back together, cycles fine the first couple of times but then it's as if the extractor ring itself relaxes or stretches, because there's soon play in the extractor (zero spring tension).
     
    Last edited: Oct 5, 2018
  4. MagnumManiac

    MagnumManiac Well-Known Member

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    The only collars I have seen that were ‘springy’ are off Mauser ‘96 actions, even then it was hit or miss as to what one you would get.
    Most are soft as you describe, the problem is making them round again once back on the bolt. When you remove them, they distort in the weakest area, which creates a ‘wrinkle’, this is hard to remove unless you force the collar around the bolt, as I do with the locking pliers and shims.
    You need good compression on the collar as you slide the extractor in place, this helps align it squarely.
    If you push on your extractor just behind the collar, how much tension can you feel?
    If the tension is light and an empty case slips under the extractors claw and wiggles, it may be that your extractor is too loose or worn.
    It’s very rare that a collar is the cause of a problem with extraction. Timing of the feed rails can and does interfere with HOW the cartridge is picked up. The extractor utilises the spring from it’s shape and also from the collar by pulling on it, if the extractor is not sprung enough, your situation can occur where it drops the case.
    I think it’s your extractor tension causing the issue, not the collar.
    You may need to replace the extractor, not the collar.

    Cheers.
     
  5. Hand Skills

    Hand Skills Well-Known Member

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    Thank you for the detailed response, that is exactly the kind of info I was looking for.

    I added some tension to the extractor - carefully inducing a set of about 5deg behind the collar.

    It was more difficult to reassemble with proper tension - I was careful with alignment and now the rifle extracts and ejects reliably.

    Still, the bolt throw is not glassy smooth. I'm now confident the extractor ring has been deformed and is not holding the extractor as close to the bolt body as it should. That or the raceway has been worn - there is some nasty scaring under the extractor ring. Either way, the extractor is not riding as tight to the bolt as it should. This is evidenced by contact with the receiver.

    Ordered a factory replacement extractor ring, will post some photos of final assembly. Might see if I can obtain the factory spec for the diameter of the raceway the collar sits in just to rule it out.