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  1. #1
    Not Banned!!!

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    Fixing a Broken Ear on an AR lower

    Some background on me before I get to the repair.

    I like to acquire broken stuff (usually via a friend or acquaintance who wants to throw it away) and try my hand at fixing it. I have bought, traded for, and been given a bunch of broken gun parts over the years and generally can get them serviceable or modify around the problems. Some are just time fillers, and not really worth it as far as money goes. These are all for my personal use, so I only have to satisfy myself with the work quality!

    I recently picked up a broken ar lower from a buddy. He had tried to remove the trigger guard (std swing down type) and had broken off one of the ears. This is an older Olympic lower, and seems to be cast, not forged.

    I neglected to take a pic of it when broken, but most of us have seen a lower with a broken off ear. I can only imagine the bubba level work he was doing as it broke... He is not a gun guy, or really a tool guy at all. Not his thing.

    My first thought was to replace the ear with a similar thickness piece of flat aluminum stock. So I put it on the mill and milled the area just behind the trigger down the thickness of the ear. Note the small piece of flat stock in the pics



    "These Rocky Mountains aren't very rocky. Yeah, that John Denver is full of SH**!"

  2. #2
    Not Banned!!!

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    I mixed up a small amount of JB Weld, and attached the repair piece to the lower. Note my exceptionally cute 1" Kant Twist clamp. If you have not tried Kant Twist style clamps, you are missing out, they are wonderful. I cleaned off any squeezed out epoxy with a q tip.





    After waiting 24hrs, I removed the clamp:


    "These Rocky Mountains aren't very rocky. Yeah, that John Denver is full of SH**!"

  3. #3
    Not Banned!!!

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    The paint job on this lower is terrible....

    After the epoxy was dry I set it back up to drill/tap a M4 holes. Counter sunk so the screw was flush.




    Back in the mill for some rough shaping.





    And after some handwork with files and sandpaper, plus I added a magpul trigger guard:


    Last edited by jdindadell; February 3rd, 2021 at 10:20 AM.
    "These Rocky Mountains aren't very rocky. Yeah, that John Denver is full of SH**!"

  4. #4
    Marksman

    Gold Member

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    Well that certainly is not going anywhere anytime soon !!!

    Good deal man, Looking good !
    "When You Go Home, Tell Them Of Us And Say, For Your Tomorrow, We Gave Our's Today"

    Voting is the responsibility of a citizen, even if voting may not necessarily be obligatory. To not vote seems to me to be an abrogation of one's responsibility as a citizen, regardless of one's politics.

  5. #5
    Donít troll me bro!

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    Pretty much what I’d have done. Good job.
    Doesnít play well with TROLLS...

  6. #6
    enthusiast

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    Mind you I have zero experience with metal work, but why not "cut" the stock metal to the proper shape before adhering it to the lower?
    Would imagine it would be easier to shape when it was not attached.
    Stephen

  7. #7
    Sic semper tyrannis

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    Dude...if thats a cast Oly arms lower...it may be a preban. Thats like gold in some states.
    Free men are not equal. Equal men are not free.

    I like guns because they're f*cking awesome.

  8. #8
    Marksman

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    Quote Originally Posted by noob View Post
    Mind you I have zero experience with metal work, but why not "cut" the stock metal to the proper shape before adhering it to the lower?
    Would imagine it would be easier to shape when it was not attached.
    Not sure if mills have bits like wood routers but he can now run a bearing/pattern bit along the original half and it will cut the exact same shape as the part the bearing/pattern bit rides on so it would make it easier. At least that is how I would do it with a wood router.

    Wish I had room for machine shop tools......

  9. #9
    Not Banned!!!

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    Quote Originally Posted by Gator 45/70 View Post
    Well that certainly is not going anywhere anytime soon !!!

    Good deal man, Looking good !
    Quote Originally Posted by Magdump View Post
    Pretty much what I’d have done. Good job.
    Thanks guys! I appreciate the kind words!
    "These Rocky Mountains aren't very rocky. Yeah, that John Denver is full of SH**!"

  10. #10
    Not Banned!!!

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    Quote Originally Posted by noob View Post
    Mind you I have zero experience with metal work, but why not "cut" the stock metal to the proper shape before adhering it to the lower?
    Would imagine it would be easier to shape when it was not attached.
    Quote Originally Posted by shrxfn View Post
    Not sure if mills have bits like wood routers but he can now run a bearing/pattern bit along the original half and it will cut the exact same shape as the part the bearing/pattern bit rides on so it would make it easier. At least that is how I would do it with a wood router.

    Wish I had room for machine shop tools......
    @ noob, it has a complex shape, and it is a really small part. I could have done a rough outline (a few thou on all sides larger) and then installed it, but I was not sure how good of a job I would be able to do at getting it lined up during the clamp and glue phase. For my skill level and machine setup it was best to just glue an oversize part in, and then trim it to fit.

    @shrxfn, I also do wood work and have used pattern/bearing bits. Very similar to what I did here. After the glue up and bolt insertion, I put the lower back in the vise and used the "good" ear to set the cut parameter. I just zeroed the bit on the good ear, then moved the table and started milling on the new ear. I had to move the receiver in the vise again to be able to mill the rough curve on the front area inside the trigger guard. I added some pics and a finished pic to help illustrate this.
    "These Rocky Mountains aren't very rocky. Yeah, that John Denver is full of SH**!"

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