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Thread: Need some help with my M1A

  1. #1
    Grand Poobah Gunco's Avatar
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    Default Need some help with my M1A

    Spent the day putting together my M1A after I just got my new GI barrel. The barrel fits perfectly. It aligns up perfect hand tight. Which means when I tighen it up it will be overclocked.

    I need to shim it. What is the best material? Where can I buy it??
    What is the best thickness? I was thinking I don't need more the 1 one thousands or 2 one thousands.

    Thoughts??
    "Courage is being scared to death - and saddling up anyway." - The Duke

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    U.N.C.L.E. Illya Kuryakin's Avatar
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    For that type stuff, I've cut my own barrel shims with scissors from stainless sheet shim stock purchased from McMaster-Carr. I've used a drum sander on Dremel to smooth out the curve but probably not really necessary. I currently have a few sheets of stainless (Rc40-45) in .003 and .005 thickness. If you think you can use it, I'll mail you some. Yours for the asking. They were very low cost items.
    Last edited by Illya Kuryakin; 04-20-2008 at 01:18 AM.


    Did I do that?

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    Gunco Regular Blazerbender's Avatar
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    That's what I love about this bunch of folks.

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    Administrator pirate56's Avatar
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    you can also peen over the edge of the bbl, it will give you a little more to tighten.

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    GuncoHolic BigAl's Avatar
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    Quote Originally Posted by pirate56 View Post
    you can also peen over the edge of the bbl, it will give you a little more to tighten.
    pretty sure I know what you mean, but do you have a picture of this?

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    Gunco Member wjkuleck's Avatar
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    The use of shims for the M1 or M14 has never been condoned. The proper course of action is to discard either the barrel or the receiver and start anew. Note that most "new USGI" barrels are takeoffs. These days it's might hard to find a USGI barrel that's really new. I've got some wraps & straws around here I could reuise to... naah.

    When economics makes it difficult to do it right as noted above, the "reclamation" procedure is to us a hammer in a strike/stroke fashion around the rear of the barrel, stretching the steel rearward. It's much like the hammer forming done by sheetmetal workers to close a gap. Really good auto restorers will resort to this techinque whenever possible rather than use lead or bondo to make the edge of a fender get to where it should be. Those who work on 1911s will recognize the strike/stroke motion as one used to shape the frame rails during slide fitting.

    For those with a lathe, the edge can be rolled to stretch the edge rearward.

    Is this a Springfield, Inc. M1A or another brand receiver? Is the barrel really, really new? We (Fulton Armory) have had to keep some special barrels on hand to make headspace with certain eras of M1A receivers with our chrome-lined Criterion by Krieger barrels (you're not going to lengthen the chamber of a chrome-lined barrel!). However, this sounds like a different challenge. If that barrel was on a rifle, it may need peening/rolling to get the proper "draw."

    This is covered in The M14 Complete Assembly Guide, though we didn't illustrate the peening process as it's so rarely needed and is pretty straightforward as described above. Maybe in a future edition.

    Regards,

    Walt
    Author, New! The M1911 Complete Owner's Guide
    Author, The M14 Complete Assembly Guide
    Author, The M1 Garand Complete Assembly Guide

    Author, The AR-15 Complete Assembly Guide
    Author, The AR-15 Complete Owner's Guide, Fourth Edition



  7. #7
    U.N.C.L.E. Illya Kuryakin's Avatar
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    Regards,

    Walt

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    Fulton Armory
    Author: The M14 Complete Assembly Guide
    Author: The M1 Garand Complete Assembly Guide

    Author: The AR-15 Complete Owner's Guide
    Author: The AR-15 Complete Assembly Guide


    Okay Walt. Geez, six posts in 4 years. Just who the hell do you think you are telling us how to do this.


    Sorry, just joking but couldn't resist.
    It's quality over quantity that really count


    BTW - why not shims? I have always heard shims are good to go with FAL builds. Is there a difference in the application or something else I'm missing. Always wanting to learn more


    Did I do that?

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    Gunco Member wjkuleck's Avatar
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    Hey, I got a personal invitation to "come back," and my Google Gadget RSS feeder started showing Gunco posts so...

    When you shim the barrel you're moving the barrel forward and essentially lengthening the chamber; with the FAL, you can always change the locking block to get headspace. Further, every thousandth you move the barrel forward is another thousandth that the case head isn't supported. With the FAL you're not only getting headspace when you change the locking block, you're moving the bolt forward when it's in battery so the the bolt head/case head/barrel relationship is maintained. Not the case with the Garand action, of course. Move the barrel forward and you get longer headspace (hey, it might still be OK, though USGI barrels are way longer in headspace than .308 SAAMI spec to start with) and less case head support.

    Aside from long headspace and unsupported case heads, I guess there's no reason not to use a shim .
    Walt's aphorism #2: Experience is the best education; other people's experience carries the lowest tuition .
    Best regards,

    Walt
    Author, New! The M1911 Complete Owner's Guide
    Author, The M14 Complete Assembly Guide
    Author, The M1 Garand Complete Assembly Guide

    Author, The AR-15 Complete Assembly Guide
    Author, The AR-15 Complete Owner's Guide, Fourth Edition



  9. #9
    U.N.C.L.E. Illya Kuryakin's Avatar
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    Thanks Walt !!

    Sounds like peening (almost had typo there, but went back to add the 'n' ) and shimming have the same effect.


    Did I do that?

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    Gunco Maniac sjohnson's Avatar
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    I'd think that sufficient peening for proper torque/timing will "crush" the shoulder and the chamber length will be effectively the same as before peening.

    Will a washer crush the same? I'm not sure.

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