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Thread: AR 15 SP1 Questions

  1. #11
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    I wonder if is a stamping error. Several years back IIRC Colt released a batch of AR15A4 rifles that were mistakenly stamped 1/9 at the factory but were actually 1/7.
    I’m told you can visually distinguish 1/12 from 1/7 rifling if you look up the bore. Check the barrel just behind the front handguard cap for a production date too.

  2. #12
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    Quote Originally Posted by jsbhike View Post
    That is weird. Have you checked to see if it really is 1/12?
    Yes i just checked with the cleaning rod procdure by putting a piece of tape on the cleaning rod then inserting the cleaning rod into the bore . initial measurement 17.0" to complete one full rotation checked measurement again 4 11/16 " or 4.687 "s so 17.0" - 4.687 "s = 12.32 = 1/12 twist rate.. there is not date code on the barrel , this was made long before Colt started stamping there barrels.. I some what recall asking about this barrel and i remember someone saying that it was on a Colt rilfe that was for export years ago , i cant remember the Colt model number ..

  3. #13
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    Quote Originally Posted by eagle20 View Post
    Yes i just checked with the cleaning rod procdure by putting a piece of tape on the cleaning rod then inserting the cleaning rod into the bore . initial measurement 17.0" to complete one full rotation checked measurement again 4 11/16 " or 4.687 "s so 17.0" - 4.687 "s = 12.32 = 1/12 twist rate.. there is not date code on the barrel , this was made long before Colt started stamping there barrels.. I some what recall asking about this barrel and i remember someone saying that it was on a Colt rilfe that was for export years ago , i cant remember the Colt model number ..

    Actually the export thing might make sense now that I think about it. For a long time some countries like Italy for instance, prohibited the civilian ownership of rifles in “military” calibers (I seem to recall that is no longer the case in Italy but I’m not sure) and thus Colt made some ARs in .222 Remington for the export market


    http://looserounds.com/2020/03/13/22...ton-colt-ar15/

    I’m wondering if some of those export A2 style variants might have retained a 1/12 twist due to their chambering.
    Have you checked the chamber on yours to verify it is actually a 5.56 spec chamber? even Colt ARs marked .223 have 5.56 chambers.
    Even if it’s not a .222 chamber, export still does make sense as overseas lighter weight .223 loadings might still have been the norm on the consumer market.
    Last edited by Circle_10; 06-03-20 at 11:35.

  4. #14
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    Quote Originally Posted by oldtimer1987 View Post
    LOL.. It must be a late production. I should get around to contacting Colt. I have been told it is an 83-85. If so that puts it towards the end of SP1s. I know the guy who pawned it was sorry, but he isn't an AR guy.
    I bought 129xxx in November 1980, so I imagine 213xxx is near the end.

  5. #15
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    There may be some info here that helps.

    http://www.biggerhammer.net/ar15/

  6. #16
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    So I contacted Colt, it was manufactured in December 1986. If I'm not mistaken the Sporter IIs were started in 1987. It would make sense that they were using what parts they had. I know I have never seen one like it.

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