Alternative to aluminum lower receiver extension

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  • Are there any that are made of steel that are REASONABLY priced? I'm on my second tube(vltor 5 pos) on my latest ar project as the first that was on there, the end plate (also vltor) key ended up destroying the threads during castle nut tightening. The one that's on there now stripped the threads but to a lesser extent so I'm gonna stick with it. The picture is of the previous tube which is what came with the Sba3 brace.

    I wasn't trying to tighten to milspec tightness (40 ft lbs!!!) more like 32 ft lbs. The TM for the m4 says 40 INCH lbs but that's retarded. That would mean 3 ft lbs and some change.

    I am aware of the v7 tube but they'd have to pay me to buy that. Don't need a a match/3 gun level tube, just don't want to end up destroying anymore extension threads.
     

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    lazarus

    Ultimate Member
    Jun 23, 2015
    13,728
    I am not aware of any. Try switching to an aluminum buffer tube nut?

    I’ve only built 2 lowers, but never had the issue you are describing. With steel or aluminum buffer tube nuts.
     
    I am not aware of any. Try switching to an aluminum buffer tube nut?

    I’ve only built 2 lowers, but never had the issue you are describing. With steel or aluminum buffer tube nuts.

    The nut isn't the problem, it's the alignment key on the end plate being of steel and the buffer tube being of aluminum. When tightening the castle nut, you get to a point where the steel key butts up against the aluminum keyway in the buffer tube and starts crushing? the softer aluminum threads.
     

    clandestine

    AR-15 Savant
    Oct 13, 2008
    37,031
    Elkton, MD
    You need to secure the Lower and the Receiver Extension when tightening or loosening the Castle Nut.

    It's a 2 person job or you need a jig from Present Arms (Costs $325.00)
     

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