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Colt AR SP1/M4

boatmatildaboatmatilda Member Posts: 3 ✭✭
edited November 2013 in Ask the Experts
I have an old (1969) Colt SP1 rifle in 223. I want to purchase a new or fairly new 5.56 upper for it. Will the Colt M4 6920 fit right onto my old lower? I know I might need a bushing for the pin. Thank you for your advice.
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Comments

  • 5mmgunguy5mmgunguy Member Posts: 3,092 ✭✭
    edited November -1
    Will need the offset bushing pin for the front.
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  • dcs shootersdcs shooters Member Posts: 10,870 ✭✭✭
    edited November -1
    I bought a Colt carbine upper for my sporter and the offset pin came with it.

    Go to www.biggerhammer.net for all AR info [;)]
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  • nmyersnmyers Member Posts: 16,890 ✭✭✭✭
    edited November -1
    But, don't buy it just because you want to shoot 5.56. All SP1's are chambered for 5.56, & can safely & reliably handle .223. It doesn't matter how the box end label is marked.

    Neal
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  • boatmatildaboatmatilda Member Posts: 3 ✭✭
    edited November -1
    Well, the SP1 is stamped 223...and from what I've read the early civilian rifles were in 223 only...this gun was manufactured in 1969...I don't think the 5.56's came out until much later. I was more concerned about the M4 feed ramp not working with my SP1.

    I knew about the pin bushing...they also make a pin that adapts the two.

    Thanks for your help!
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  • SpartacusSpartacus Member Posts: 14,415
    edited November -1
    quote:Originally posted by boatmatilda
    Well, the SP1 is stamped 223...and from what I've read the early civilian rifles were in 223 only...this gun was manufactured in 1969...I don't think the 5.56's came out until much later. I was more concerned about the M4 feed ramp not working with my SP1.

    I knew about the pin bushing...they also make a pin that adapts the two.

    Thanks for your help!


    5.56 nato went into service in 1962.
    your SP1 can handle it w/o issue.

    tom
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  • TxsTxs Member Posts: 17,809 ✭✭✭
    edited November -1
    quote:Originally posted by Spartacus
    5.56 nato went into service in 1962.
    your SP1 can handle it w/o issue.Agreed.

    Despite what their lower receivers and magazines were stamped with at one time, Colt always used - and continues to use - a 5.56 chamber on almost all of their rifles. The only .223 chambered Colt AR's you'll ever see are from relatively small runs of special models.

    One way or another, on any AR you should refer to the barrel marking rather than the lower receiver rollmark due to this rifle's modular design.
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