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  1. #1
    50 CAL TackleberryMCS's Avatar
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    Latest Retro Build

    Since last year, I have been trying to get two more M16A1 clones built. It has been a long wait for the Nodak Spud receivers. Fortunately, Harlan told me about a blem set that was available and I was able to score that to get one of the builds done. After picking up the receiver set and CH this morning from my FFL, the late 1967-1970 M16A1 clone is done. It even has a correct C MP C barrel. Internals (FCG modified to SP1 specs)and furniture are original M16 parts. I did my own BFPU finish as usual. It may be sometime around October or November before I get the 1971 version done.














    Last edited by TackleberryMCS; 07-07-2018 at 11:58 AM.
    "A Bad Day At The Range Is Better Than A Great Day At Work"


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  3. #2
    45 ACP Plinker's Avatar
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    WELL done!

    Enjoy updates on those retro’s you put together.

    Maybe you can give me direction on a replacement barrel for my Colt SP-1 built in 1971.
    Its the 20” pencil barrel with 1-12 twist. Confirmed a few months ago that accuracy is suffering bigtime after many thousand rounds by me.
    No telling how many rounds previous owners fired.
    Groups are pretty big at 25 yds off bags with the SP-1 but can almost make rounds touch with my PSA Carbine.

    Both with iron sights.

    Good job and thanks in advance for vender tips!
    Location: South of Molino/North of Cantonment

  4. #3
    50 CAL TackleberryMCS's Avatar
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    Quote Originally Posted by Plinker View Post
    WELL done!

    Enjoy updates on those retro’s you put together.

    Maybe you can give me direction on a replacement barrel for my Colt SP-1 built in 1971.
    Its the 20” pencil barrel with 1-12 twist. Confirmed a few months ago that accuracy is suffering bigtime after many thousand rounds by me.
    No telling how many rounds previous owners fired.
    Groups are pretty big at 25 yds off bags with the SP-1 but can almost make rounds touch with my PSA Carbine.

    Both with iron sights.

    Good job and thanks in advance for vender tips!
    Finding an original and correct barrel for your SP1 is a difficult task. Gunbroker is probably the best bet. You can get a new 20" 1/12 barrel assembly from Brownells for around $250. It includes the slip ring assembly and FSB. You will have to change out the front sight post with a correct round type since they come with the square A2 type post. Brownells also have the correct sight post available. These barrels are made by Ballistic Advantage. You can replace the barrel you have and hang on to it and just continue shooting the SP1 with a new replacement barrel. If you every decide to sell the SP1, you can sell the original barrel with it.

    https://www.brownells.com/rifle-part...prod97904.aspx

    https://www.brownells.com/rifle-part...ampaign=Itwine
    "A Bad Day At The Range Is Better Than A Great Day At Work"


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  6. #4
    50 CAL Daezee's Avatar
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    Plinker,

    Sounds like your bbl is a good candidate to have its throat measured by my throat erosion gage.

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  8. #5
    50 CAL TackleberryMCS's Avatar
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    Quote Originally Posted by Daezee View Post
    Plinker,

    Sounds like your bbl is a good candidate to have its throat measured by my throat erosion gage.
    That may not be a bad idea.
    "A Bad Day At The Range Is Better Than A Great Day At Work"


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  10. #6
    45 ACP Plinker's Avatar
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    Thanks Bruce.
    I would appreciate that.
    Want to blame me/ammo/you name it,,,,anything but the gun for those big groups.
    Sure would like to be absolutely sure.

    Please let me know when your available sometime next week.
    Regards,
    Tony


    '
    Location: South of Molino/North of Cantonment

  11. #7
    50 CAL Red's Avatar
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    Great job James!! Looks awesome!!

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  13. #8
    45 ACP Plinker's Avatar
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    James, please pardon my hijack to place this picture. Wanted you and Bruce to see the improvement after just a thorough cleaning of the chamber.
    Bruce’s erosion gauge measured a 3 and said rifling looked great and with that number and visual inspection the accuracy should still be there.
    He had to leave ERGC to go shooting at Pensacola Rifle & Pistol Club before I could print a group.
    Here is what I could do at a 1” dot @ 25yards.

    Name:  F2A3D9BF-F6DE-4B9E-9DD3-ADED1A1580B0.jpg
Views: 62
Size:  99.6 KB

    I can live with this with 65 year old eyes and stock trigger.
    Thank You Bruce and James!
    Saved me several hundred dollars that can be spent on somethin else!
    And thank you GCGF!

    Edit: Picture needs rotating clockwise 90 degrees. Group was mostly under dot. 5 shot group with a bad flier and most likely my error with the stock trigger.
    Last edited by Plinker; 07-11-2018 at 04:52 PM. Reason: How do you rotate these pictures??
    Location: South of Molino/North of Cantonment

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  15. #9
    50 CAL TackleberryMCS's Avatar
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    Quote Originally Posted by Plinker View Post
    James, please pardon my hijack to place this picture. Wanted you and Bruce to see the improvement after just a thorough cleaning of the chamber.
    Bruce’s erosion gauge measured a 3 and said rifling looked great and with that number and visual inspection the accuracy should still be there.
    He had to leave ERGC to go shooting at Pensacola Rifle & Pistol Club before I could print a group.
    Here is what I could do at a 1” dot @ 25yards.

    Name:  F2A3D9BF-F6DE-4B9E-9DD3-ADED1A1580B0.jpg
Views: 62
Size:  99.6 KB

    I can live with this with 65 year old eyes and stock trigger.
    Thank You Bruce and James!
    Saved me several hundred dollars that can be spent on somethin else!
    And thank you GCGF!

    Edit: Picture needs rotating clockwise 90 degrees. Group was mostly under dot. 5 shot group with a bad flier and most likely my error with the stock trigger.
    One thing my father and the Marine Corps taught me was the importance of a really clean weapon. I clean my weapons after every use. On my ARs, that means running a bore brush down the barrel followed by several patches with CLP until clean. A clean barrel is paramount to good performance and accuracy.
    "A Bad Day At The Range Is Better Than A Great Day At Work"


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  17. #10
    50 CAL Daezee's Avatar
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    The TE gauge I used has marks from zero to 10, with each indicating the rifling has worn 0.1". US Military standards for combat use are when the TE has reached 1", the bbl is rejected. Note: I do not know what the Current standards are (I do not know if the military still uses a throat erosion gauge on the M16, but at least they used to have 2 of them, one for chrome lined bbls and one for non chrome lined bbls), 1" was the standard from the 1930's at least until the 1980's when I retired. A serious target shooter would have higher bbl wear standards or replace the bbl when the accuracy drops regardless of rounds fired or what a gauge reads. The military also had the standard of "6" or less for 30 caliber bbls that would accompany troops overseas (IIRC...my Rebuild Standards manual was lost in a house fire)...in other words they wanted enough bbl life left since overseas troops may not have facilities for installing new barrels as easily as in CONUS.

    I was not an armorer in the service, only a reasonable knowledgeable individual who took a Marine Corps course on inspection and repair of firearms so I could learn more and get to keep the course materials and manuals if I passed the course. As part of my shooting hobby, I am keeping firing records and throat wear measurements on my rifles. FWIW, chrome bbls are wearing slower than nitrided.

    Ideally one would have the TE recorded for when the bbl was new. From my experience, AR .223/5.56 bbls when new typically read 1 to 1 1/2. Plinker's was "3" or 0.3". Should have plenty of life left. The top of the lands at the chamber end had some darkness to them, but not in the grooves. I suspect there is copper fouling on top of the lands. No pitting was noticed.
    Last edited by Daezee; 07-11-2018 at 07:05 PM.

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