Colt m16 upper question

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  • Kuffaar

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    Jan 13, 2019
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    Hey guys I'm looking on gun broker and wanting to get an original a1 style upper. My question is will a colt upper marry to a milspec lower? I know the trigger pins are larger on their lowers but unsure about anything else being different.

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    DAVE_M

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    Assuming by A1 style you mean a reproduction upper, then yes, it will fit a modern lower.
    From a collector's standpoint, I don't see the point in placing an old upper on a new lower.

    I'm also assuming you intend to shoot it.
     

    Kuffaar

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    Assuming by A1 style you mean a reproduction upper, then yes, it will fit a modern lower.
    From a collector's standpoint, I don't see the point in placing an old upper on a new lower.

    I'm also assuming you intend to shoot it.
    I do intend to shoot it but its just the upper attached I have a screen shot. Will not be using an original barrel.
    1dfda673c61c436cb522a05e2d7b8599.jpg


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    103M 95G

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    A newer standard lower front take down pin hole is like .250, where as some of them older colts have a .312 hole. you would probably need an offset pin for it to work.

    BTW that kit looks to have an M16 hammer, sear, selector, and possibly the trigger

    And why would they cut the firing pin?
     

    dwr461

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    I had a Colt smooth side SP1 upper lying around. I mated it with a M4 barrel and a modern machined lower with PSA lower parts. It sighted in with M16a1 rear sight on the M4 front sight in under ten rounds. I’ve shot it in a couple of matches and it has been reliable. It is reasonably accurate for competition but I’ve not printed it at a range.


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    Kuffaar

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    A newer standard lower front take down pin hole is like .250, where as some of them older colts have a .312 hole. you would probably need an offset pin for it to work.

    BTW that kit looks to have an M16 hammer, sear, selector, and possibly the trigger

    And why would they cut the firing pin?
    Thanks for the info. That is what I was wondering.
    Not sure how you would know the firing pin would be cut though?

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    dwr461

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    It’s my memory that Colt used the larger pins on some commercial AR’s. There are adaptors from Brownells for example that will let you use them. So it’s not a problem.


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    Kuffaar

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    It’s my memory that Colt used the larger pins on some commercial AR’s. There are adaptors from Brownells for example that will let you use them. So it’s not a problem.


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    Did your sp1 have different sized take down pins?

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    340six

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    My Original Colt SP1 has large pin. In reality it is screw a head. They make as,stated above a large _ small conversion pin. Since An AR-15 for some is like an Adult Lego Set.
    Not sure what else there is to say.
     

    Kuffaar

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    Thanks everyone. Y'all cleared up my question. Many thanks

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    DAVE_M

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    If you just want a retro build, you can source the appropriate parts. I would not purchase a kit like that from Gunbroker unless you absolutely know what you're getting yourself into.
     

    dwr461

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    Yeah there was a sale earlier in the month for brownell’s retro AR’s for just under $1k. That’s a pretty darn good price on brand new warrantied retro AR’s.

    Dave


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