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Thread: Mid length rail on a 6920

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    Mid length rail on a 6920

    Hi....I'm a newbie awaiting delivery of my 6920 this coming week. I have a few technical questions. I'm considering putting a mid length free float rail on it instead of a carbine length RAS. The Knight's mid length is a bit over 9". I presume I'll have to remove the front sight / gas block and replace it with a low profile one. Is removing the old / replacing with a new gas block an easy procedure? Any suggestions regarding manufacturer choices for the new block? I'm planning on putting a set of YHM / Troy / or GG&G BUIS on the top rail when it's installed.

    Thanks!

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    Easy is relative to your mechanical abilities. I don't replace the FSB with a low profile gas block, I mill/grind them down to fit under a rail/tube. That way it's still pinned and can't move.

    This is an old pic when my 10" LMT had a FSB and a KAC RASII rail.


    Then I 'shaved' the FSB and installed a 9" DD Lite Rail.



    Nowadays it's looks like this.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

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    I'm with Robb, I greatly prefer shaving down the FSB. I've paid to have it done once and I've done it myself once. Wasn't too difficult at all. When I was done I just sprayed it with hi-temp grill paint and it's still chugging along just fine. If it was going to be exposed to bumps and scratches I might have opted for a tougher finish, but since it's protected by the rail I'm not concerned.

    If you don't feel comfortable doing it yourself, ADCO will do it for you. When they did mine I bought the DD 9.0 rail from them and they didn't charge me to install the rail, just for the price of the rail and the price to shave the FSB. Don't know if that's still their deal or not.

    Here's some pics of my shave job (some in-progress and some complete)


















    and the final products


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    I forgot to mention since you said this was going on a 16" barrel. DD makes 10" Lite Rail now too which will be just a little longer which is nice. A 9, 10 or 12 rail will fit. DD is now milling out a section of the back end of the rail which will allow it to slide over a gas block during installation for easier less tricky installation. It's similar to what ADCO was doing.

    Here's my 12.5" SBR that started with a 7" Lite Rail, then I shaved the FSB and added a 9.5" Daniel Defense RISII MK18 rail.

    Before:


    After:




    Then it's latest pic, just yesterday:
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

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    Thanks for the quick replies. .....great pics too. I'm not adverse to cutting it down and or milling it myself. There's a shop that I have access to which has a bandsaw and enough grinders for me to do the work myself. Any suggestions for removing the front handguard cap?
    Last edited by intrepidagent; 05-25-08 at 10:35. Reason: additions

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    The handguard cap will come off when you take the FSB off.

    In case Robb and I weren't clear, I wouldn't (and I don't think he would either) advocate doing this work with the FSB still on the barrel. You can see from my pics that it's removed and clamped in a vice.

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    Quote Originally Posted by rob_s View Post
    The handguard cap will come off when you take the FSB off.

    In case Robb and I weren't clear, I wouldn't (and I don't think he would either) advocate doing this work with the FSB still on the barrel. You can see from my pics that it's removed and clamped in a vice.
    Correct. I'd only do it on the barrel if you had a non removable muzzle device. Since your adding a DD Lite Rail you'll have to take it off anyway since the DD has it's own proprietary barrel nut.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

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    The more I see gotm4's rail/light setup, the more I like it. I photoshopped this using LaRue's weapon profiler to get an idea of how the 9" rails look with a 16" barrel. It doesn't look as bad as I thought it might...


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    Quote Originally Posted by lindertw View Post
    The more I see gotm4's rail/light setup, the more I like it. I photoshopped this using LaRue's weapon profiler to get an idea of how the 9" rails look with a 16" barrel. It doesn't look as bad as I thought it might...
    It works very well. I used my 10" SBR set up this way for the mods/staff Vickers class and it worked very well for the low-light night stuff we did.

    Here's some pics of a shaved gas block and barrel, the gas block has been sandblasted after shaving and refinished with flat black Norrells moly before reassembly.





    Here's one I recently did while it was still attached to the barrel since I was installing a 10" Troy rail (which clamps onto the stock/OEM barrel nut) and the muzzle device was perm. mounted.

    After shaving and sandblasting:



    after refinish w/Norrells:

    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

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    Quote Originally Posted by lindertw View Post
    The more I see gotm4's rail/light setup, the more I like it. I photoshopped this using LaRue's weapon profiler to get an idea of how the 9" rails look with a 16" barrel. It doesn't look as bad as I thought it might...

    IMHO if you're going that route I'd go with a 10.0 or 11.0 depending on your preference and what each maker has available.

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