Stock Cross-bolts Explained

Discussion in 'General Sako Discussions' started by South Pender, Aug 10, 2019.

  1. South Pender

    South Pender Well-Known Member

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    I've often wondered about the function of the rear stock cross-bolt (the one behind the magazine) on centerfire rifles--Sako and others. I had thought that the front cross-bolt (which is the only one on many centerfire rifles) was to somehow reinforce the recoil-lug area of the stock. However, after an examination of the inside of the stock on my new Sako 85 (pic below), both bolts seem to me to be far too thin and light to absorb much shock.

    So, what is their function? My guess is that it is to prevent the stock from bowing out around the magazine area upon recoil, since the broad heads of the bolts might keep the stock from swelling laterally.

    Is this it or am I missing something?

    [​IMG]

     

  2. Tomball

    Tomball Well-Known Member

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    Cross bolts been around a long time in various rifles. I have been told several times to prevent stock splitting with guns with heavy recoil. If it prevents bowing, it is preventing splitting. My 2 cents.
     
  3. icebear

    icebear Well-Known Member

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    As Tomball says, to prevent the stock from splitting under repeated recoil. The crossbolt distributes and dissipates the recoil force, preventing the impact from concentrating at a weak spot in the wood. It isn't perfect, but it helps.
     
  4. Sean Hodges

    Sean Hodges Well-Known Member

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    To add to the above, crossbolts do not need to be overly heavy to provide a level of reinforcement in the front and rear of the magazine area, as well as the rear tang A small amount of flex is not a bad thing in comparison to too much rigidly. Also, some crossbolts have a bearing surface which contacts the rear portion of the recoil lug. This is evident in older Sako rifles. In fact the lug must be rolled if removed, back into the correct orientation to be able drop the action into the stock correctly.
     
    Last edited: Aug 11, 2019
  5. South Pender

    South Pender Well-Known Member

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    I had thought, when I disassembled the rifle, that the cross-bolts would be beefy all the way through--close in diameter to the bolt heads (that you see on the outside of the stock)--and thus able to absorb a lot of the recoil energy, like the type Sean Hodges describes which contact the back of the recoil lug. In my 85, however, this is not the case at all. I didn't measure the diameter of the interior of the two bolts, but this portion looked thin--maybe 1/16" or perhaps 3/32" so really unable to absorb much energy. Each bolt has large-diameter heads on each side, however--a little over 1/2". So it seems to me that these bolts must be primarily to keep the stock from outward flexing around the magazine section under the force of recoil, rather than directly absorbing recoil energy.
     
    Last edited: Aug 11, 2019
  6. Sean Hodges

    Sean Hodges Well-Known Member

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    Although, they may be of lighter material, I believe the crossbolts accomplish both scenarios, springing out laterally and reduced potential of splitting material rear of the front lug. Take care.
     
    Last edited: Aug 11, 2019
  7. icebear

    icebear Well-Known Member

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    This is the case with the Mosin Nagant military rifle, improved versions of which were Sako's principal product from its founding through the WWII era.
     
  8. icebear

    icebear Well-Known Member

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    The recoil lug does not absorb energy. Being both small and rigid, it could not serve that function. It is there to strengthen the stock.
     
  9. stonecreek

    stonecreek SCC Secretary Forum Owner SCC Board Member

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    I have no idea about the crossbolt arrangement on the Sako 85 as I've never seen the inside of one.

    On the L61R, which had only a front crossbolt, the early ones used a flat-sided bolt which bears against the recoil lug of the action and thus serves to spread the force of recoil across a wider area of stock wood. Later L61R rifles used a round crossbolt which served the same purpose, the only difference being that the recoil lug bears against just the tangent of the round cross bolt and not a flat face. Either is probably equally effective; but my prejudice favors the flat one.

    The Sako A-V rifles used the same system. However, when the physically larger "Tikka" trigger replaced the original Sako #4 trigger midway in the A-V run, the new trigger required that more wood be removed from the inletting to make room for it, thus potentially weakening the stock in that area. So, Sako added the rear crossbolt to reinforce the stock where there had previously been a wood bridge between the two sides of the stock. The rear crossbolt is meant to keep the relatively thin wood in that area from flexing under recoil.
     

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