Receiver Rough bolt cycling

Discussion in 'Tips and Tricks for gunsmithing your own Sako' started by Bucktote, Jul 15, 2021.

  1. Bucktote

    Bucktote Well-Known Member

    Messages:
    150
    Likes Received:
    44
    Country Flag:
    USA
    State/Region:
    US Georgia
    After shooting, while cleaning my Forester I found the bolt at the rear of the recycleing stroke seemed rough. After lubricating the bolt It still seemed to hang up toward the rear. I remembered reading somthing about a similar problem in a post on the site.
    " Check the action screws" sure enough after loostening the rear screw some, the action was smooth as it should be. Reason for the problem action screw too long !. Remedy loosten the screw a bit, but how much is too much? Does anyone know if a bolt die for that thread is available? I would like to grind the screw a bit shorter, but am afraid or ruining the threads on it. A 60 year old stock must have shrunk a bit in that torqued area and allowed the action screw to interfear with the bolt travel. Could possibly make a tapered ( cone shaped ) washer to go between the tapered head screw & the wood??

     
    Last edited: Jul 15, 2021

  2. tilleyman

    tilleyman Active Member

    Messages:
    43
    Likes Received:
    57
    Country Flag:
    Australia
    State/Region:
    AU Victoria
    Common enough problem, unless you have access to a lathe, filing off 0.5mm or so from the end of the action screw is the usual fix... use soft jaws in the vice to avoid galling the threads.
    Mount the screw in a drill (again protect the threads with some masking tape) and spin held against a fine file.
    Then work through 180-220-240-360 grades wet and dry paper (lubricated with some kero).
    Use a hard flat backing to the paper to keep edges crisp.
    A dab of cold blue will make the modified end look factory.
    Putting a cone washer under the head would also work but would of course make the countersunk head then sit proud... bit ugly.
    Thread size is a common M6x1.0mm, sometimes a plug tap in that size is useful to carefully clean out decades of varnish, bedding compound or previously slightly cross threaded areas where some Bubba has been too heavy handed on the screwdriver!
     
    Last edited: Jul 15, 2021
  3. gunner620

    gunner620 Well-Known Member

    Messages:
    547
    Likes Received:
    32
    Country Flag:
    USA
    State/Region:
    US Florida
    Bucktote, Sako used shims between bottom metal as needed to align the bottom metal with the stock line, The action screws went through the shim. As the shims were only used where needed there could have been one or more or no shims used at either action screw location. Is it possible that one could have been misplaced or used in a location where it was not needed ? I believe the action has been removed a few times lately when work was completed. The original shims like a lot of other things for Sako's are hard to find so you may have to make your own, Good luck Jim
     
    Old Hippie and icebear like this.
  4. paulsonconstruction

    paulsonconstruction Sako-addicted

    Messages:
    3,636
    Likes Received:
    721
    Country Flag:
    USA
    State/Region:
    US Iowa
    Modifying the action screws or using a "cone"washer is a fool's errand & completely unnecessary. Just do what gunner620 suggested & put some metal shims between the trigger guard & the stock inletting at the rear action screw so the action screw doesn't protrude to interfere with the bolt. Why go to all the trouble the grind the end of the screw & cold blue it, when a simple invisible shim will solve the problem? Doesn't have to be "an original" Sako shim. Anybody can make one with some shim stock, some tin snips, a file, & a drill. "Even a cave man can do it". I suspect your wood stock has "shrunk" a bit over the years! Amazing how people can come up with a complicated fix for a simple solution.
     
  5. icebear

    icebear Sako-addicted

    Messages:
    1,710
    Likes Received:
    885
    Country Flag:
    USA
    State/Region:
    US Arizona
    Don't worry about messing up the threads. If the thread closes up at the end, just take a knife-edge miniature file or riffler and open it up again. I've done it more times than I can count.

    And Gunner620 makes a good point about the shims. If the bottom metal is noticeably below the wood line at the rear, you might just be missing a shim or two. Easy enough to make if you can't find a missing shim and/or don't have spares. If a shim has been lost, you will most likely see the imprint of the shim on the wood.

    The shrinkage theory remains highly likely.
     
  6. tilleyman

    tilleyman Active Member

    Messages:
    43
    Likes Received:
    57
    Country Flag:
    Australia
    State/Region:
    AU Victoria
    How is taking 0.5mm off the end of a screw and dressing it square in a 5 minute job MORE complicated than finding the correct shim stock, measuring the stock recess, marking out the correct shim size, clamping it between two pieces of wood to drill the hole (because you can't drill hardened shim stock easily without it climbing the drill and distorting, or there are specialist drills ground with less rake and point angle) cutting with tin snips, filing to final shape and removing sharp edges?
     
    Last edited: Jul 17, 2021
    Old Hippie likes this.
  7. stonecreek

    stonecreek SCC Secretary Forum Owner SCC Board Member

    Messages:
    7,667
    Likes Received:
    1,583
    Country Flag:
    USA
    State/Region:
    US Texas
    Either shortening the screw or shimming between the stock and the bottom metal will cure your problem. The "more" proper one to do is probably the shim since it is most likely shrinkage of the wood which has resulted in the screw, which presumably didn't grow in length, to protrude. Shimming will result in not only curing the "too long screw" problem, but will likely also make the bottom metal more flush with the wood.

    I've done both fixes in the past, depending on which appeared to be more appropriate.
     
    tilleyman likes this.
  8. Bucktote

    Bucktote Well-Known Member

    Messages:
    150
    Likes Received:
    44
    Country Flag:
    USA
    State/Region:
    US Georgia
    Thanks fellows,
    All the suggestions look easy enough to accomplish. How tight should the rear action screw be? I have heard mearly snug enough to be firm but not as tight as the front screw. I think the difference between the wood & the metal will be the deciding factor, now that I know what the problem is. Kind & gentle comments are always welcome. B/T
     
  9. caberslash

    caberslash Member

    Messages:
    22
    Likes Received:
    27
    Country Flag:
    UK
    State/Region:
    UK Orkney
    @Bucktote if you want a single shim off an original L series, PM me your address.

    Don't have any use for it as the dealer I bought it from lost the other one when they had it in to clean up the short chamber (long story!), and lost a shim, so I bedded my bottom metal and have no use for it.
     
  10. icebear

    icebear Sako-addicted

    Messages:
    1,710
    Likes Received:
    885
    Country Flag:
    USA
    State/Region:
    US Arizona
    Sounds about right. I get both screws nice and tight but I tighten the front one first and crank down on the rear just a hair less than the front. I'd say that if your bottom metal is visibly below the wood line you need a shim and if it's not you need to grind the screw. That's how I would do it if it were my gun.
     
    Bucktote likes this.
  11. tilleyman

    tilleyman Active Member

    Messages:
    43
    Likes Received:
    57
    Country Flag:
    Australia
    State/Region:
    AU Victoria
    Just happens I have an example on my L579 that I'm rebarrelling... someone in the past simply hacksawed off the end of the screw at an angle!
    If you cut half through a M6x1.0mm nut it will form a collet and enable the drill chuck to clamp down firmly without damage to the threads.
    Sako L579 screw .jpeg Sako L579 screw dressed.jpeg
     
    Bottom Gun, Bucktote and icebear like this.
  12. icebear

    icebear Sako-addicted

    Messages:
    1,710
    Likes Received:
    885
    Country Flag:
    USA
    State/Region:
    US Arizona
    Clever. Why didn't I think of that? All kinds of applications for that idea.
     
    Old Hippie and tilleyman like this.
  13. kevinlg

    kevinlg Well-Known Member

    Messages:
    673
    Likes Received:
    141
    Country Flag:
    USA
    State/Region:
    US Texas
    Many ways to skin a cat.......
    I settled on this one, long ago.

    Place a small disc of masking tape over the screw head. Open a cordless drill 3/8ths chuck ALL the way....and place the screw head all the way to the bottom. Now.........VERY, VERY carefully close the chuck around the screw shaft WHILE gently"giggling" the screw.....to make sure the jaws bottom out on the screw shaft, and NOT the head.
    Now....using the depth shaft on your calipers.....measure the amount of screw protruding past the jaws. Having earlier determined the amount of metal to be removed......you can grind/file/sand down to a finished length.
    I usually use the disc surface of a Dremel cutoff wheel(after clamping the drill flat to the bench, with drill and dremel rotating in opposite directions).
    It's easy to trim a screw to within a couple thou of desired length.
    To finish up.....I index the screw and finish sand across the stub with 320 silicon-carbide. Cold blue.......and it's almost a perfect match to the rear tang groove bottom. Almost can't see the hole....

    Clear as mud....huh?? :)

    Hope this helps.

    Note: The pic is of my old primer pocket uniforming set-up. I use the drill similarly when shortening screws.

    [​IMG]
     
    Last edited: Jul 18, 2021
    Bucktote, sakojim and tilleyman like this.
  14. Bucktote

    Bucktote Well-Known Member

    Messages:
    150
    Likes Received:
    44
    Country Flag:
    USA
    State/Region:
    US Georgia
    Thanks for your kindness I have some on the way./ Keep well & all the Best! B/T
     
    caberslash likes this.
  15. tilleyman

    tilleyman Active Member

    Messages:
    43
    Likes Received:
    57
    Country Flag:
    Australia
    State/Region:
    AU Victoria
    Last edited: Jul 19, 2021
  16. kevinlg

    kevinlg Well-Known Member

    Messages:
    673
    Likes Received:
    141
    Country Flag:
    USA
    State/Region:
    US Texas
    How does the current aftermarket screw head polish/finish compare to the old factory L and A series screws?

    Back in the day.....the finish on Forster and B-Square screws was not all that great. I restored/polished and sent for bluing a few dozen screws. Years on.....it was worth the effort.
     
  17. icebear

    icebear Sako-addicted

    Messages:
    1,710
    Likes Received:
    885
    Country Flag:
    USA
    State/Region:
    US Arizona
    The B-square ones used to be Allen head, not slotted, and the finish was dead flat. Don't know if that is still the case or not.
     
  18. tilleyman

    tilleyman Active Member

    Messages:
    43
    Likes Received:
    57
    Country Flag:
    Australia
    State/Region:
    AU Victoria
    Good point, though the finish on the B Square hex head ones I bought was high gloss and very good... seems they were late production.
    The Forster screw heads however are not polished, look to be linished to about 240 grit... and end up looking a bit satin.
    As you say they can easily be polished up and reblued to match your particular Sako if required....

    Forster Sako screws.jpeg
     
    Last edited: Jul 20, 2021
  19. kevinlg

    kevinlg Well-Known Member

    Messages:
    673
    Likes Received:
    141
    Country Flag:
    USA
    State/Region:
    US Texas
    Here are some B-Square screws that I re-worked.....and then used on my single-shot L461 17-222 PD project build, years ago.

    (edit: Sorry for lousy pic.)

    [​IMG]
     
    tilleyman likes this.

Share This Page