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FAL Locking shoulder

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9 comments

  • quickmajik
    buy the headspace guage and do it right.
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  • iwannausername
    You will need the headspace gauge and a few locking shoulders, OR you will need to screw it in as much as possible, get the front sight timed properly, and measure to take a closer guesstimate of what ls you need.

    There is probably a howto on falfiles.com in the forums there
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  • drobs
    I watched Marc Krebs of Krebs Custom build one on a DSA receiver in about 1 hour. He had bought 4 STG 58 kits and worked out a deal to trade one of the kits to DSA for one of their receivers.

    He had to take the shoulder of the barrel down (on his mill) to get it thread in correctly to the receiver. Head spacing was something else too - multiple locking shoulders as I recall.

    I've built 4 AK's at home. I don't think I would attempt a FAL build after watching him. I don't have the tools he has.


    His one caution to me was -- make sure you grease the barrel threads before attemtping to screw the barrel on. Don't play around with an ungreased barrel and receiver.

    quote:Originally posted by richbug

    No grease required on the barrel threads. You could use it if you wanted, but it will seep out and mess up your refinish job.


    How exactly do you use a mill to modify a barrel shoulder? Any DSA I have built has timed up properly without any machining.

    The current DSA's are using LS's on the shorter end of the scale, I have seen .248-.254", everyone gets their panties in a bunch when it comes to HS. You have a .004" range to get it right and safe. Bigger space will be more reliable, tighter will likely be more accurate, and brass will last longer.

    You don't need multiple LS's, you need a go gage, a No Go gage, and something to use as gauge pins. Drill bit shanks can be used as pins.



    My terminology may be off but this was a horizontal (mill?) that spun the barrel to alow him to take some material off the the barrel where the threads met the barrel. I don't believe he took the material off the threads.
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  • richbug
    quote:Originally posted by drobs
    I watched Marc Krebs of Krebs Custom build one on a DSA receiver in about 1 hour. He had bought 4 STG 58 kits and worked out a deal to trade one of the kits to DSA for one of their receivers.

    He had to take the shoulder of the barrel down (on his mill) to get it thread in correctly to the receiver. Head spacing was something else too - multiple locking shoulders as I recall.

    I've built 4 AK's at home. I don't think I would attempt a FAL build after watching him. I don't have the tools he has.





    His one caution to me was -- make sure you grease the barrel threads before attemtping to screw the barrel on. Don't play around with an ungreased barrel and receiver.



    No grease required on the barrel threads. You could use it if you wanted, but it will seep out and mess up your refinish job.


    How exactly do you use a mill to modify a barrel shoulder? Any DSA I have built has timed up properly without any machining.

    The current DSA's are using LS's on the shorter end of the scale, I have seen .248-.254", everyone gets their panties in a bunch when it comes to HS. You have a .004" range to get it right and safe. Bigger space will be more reliable, tighter will likely be more accurate, and brass will last longer.

    You don't need multiple LS's, you need a go gage, a No Go gage, and something to use as gauge pins. Drill bit shanks can be used as pins.
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  • tmcbp
    So if I was going to use drill bits to do this..., the diameter of the bit would be the same size as the locking shoulder that I would need?
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  • DRP-AZ
    email sent.
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  • richbug
    quote:Originally posted by tmcbp
    So if I was going to use drill bits to do this..., the diameter of the bit would be the same size as the locking shoulder that I would need?


    Yes, if the shank(round part of the bit, when inserted into the LS hole, closes on a go, but not a no-go), you are golden and that is the size LS you need.

    Any precision round piece of steel could be used.

    With a current DSA, I would start with a 1/4", .250"
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  • Tailgunner1954
    quote:Originally posted by drobs
    My terminology may be off but this was a horizontal (mill?) that spun the barrel to allow him to take some material off the the barrel where the threads met the barrel. I don't believe he took the material off the threads.


    Umm ya, it's just off a tad. That piece of machinary is called a lathe.
    Lathe, work turns, cutter moves in 2 directions. Used for round work pieces.
    Mill, work is stationary clamped to a table that moves in 2 directions, cutter turns. Looks like a super heavy duty drill press. Used for the other than round work pieces.
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  • amparts
    There are not only different sizes of locking shoulders (around 14) there are four (4) different diameters. The different diameters come into play to adjust for the actual size of the hole. Not only for different mfg but to allow for wear. I have most all sizes, plus specials including ones to be ground to save some combinations of barrels and receivers. All brand new factory parts. The Australian manual has the best instructions for picking the correct locking shoulder diameter and size, original manual $20.00, this is the manual TAPCO copied and used to sell a reprint.
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