Swapping uppers on a lower ok?

Discussion in 'AR-15 Discussion' started by tomykay12, Jun 3, 2014.

  1. tomykay12

    tomykay12 New Member

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    Maybe dumb newbie question, but is it ok to have, say, more than one upper for the same lower? maybe a lightweight carbine with open sight setup, and a longer, heavier upper equipped with optics to reach out a bit? Any pitfalls here? Just curious for now, and thanks, tk
     
  2. Point6liter

    Point6liter New Member

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    You shouldn't have any issues at all. I have four uppers and two lowers (one rifle lower, one pistol lower) and swap uppers out with no issues. I would just test fit them and make sure they fit well, and there are no clearance issues with any of the moving parts.
     

  3. Davo45

    Davo45 New Member

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    As long as you don't put a pistol upper on a rifle lower creating an illegal SBR you should be fine.
     
  4. SSGN_Doc

    SSGN_Doc Well-Known Member

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    No problem at all. The military SPR was originally a concept of being an extra upper to add a compact precision option for operators equipped mostly with carbines. If they had a need for some intermediate range precision they could simply take off the carbine receiver and instal the Special Purpose Receiver. It eventually evolved into a Special Purpose Rifle.
     
  5. Triumphman

    Triumphman Active Member

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    You can even swap to different calibers. Just make sure that it's compatible with the correct type Lower used. Can't use 7.62(308) caliber Upper with AR15(5.56/223) Lower. There's others, but I think you get the idea.
     
  6. rn-cindy

    rn-cindy Active Member

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    Swapping uppers on a lower...lol. I thought this thread was going to be about something way different......:)
     
  7. tomykay12

    tomykay12 New Member

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    Hmmmn

    Thankyou....tk
     
  8. Ibmikey

    Ibmikey Active Member

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    As noted swapping is easily done but for just a few dollars more you can build a lower and have another complete rifle. Of course at that point you will probably want to modify the upper....then maybe a longer/shorter barrel would be nice and it could be built into an extra upper receiver....but then................and the AR Mania goes on and on
    :)
     
  9. tinbucket

    tinbucket Well-Known Member

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    Only thing I have observed, is soem uppers won't mate as close as I like, on a Colt AR 15 lower . It was done on purpose by Colt, supposedly keep people from using M16 uppers along with other things like blocks, in the lowers, different pin sizes etc.. Makes no sense at all. A Colt upper, using adapter pin leaves more of a gap between upper and lower. You want them to mate firmly together. I read some concerns about exact match when using some Bushmaster lowers and other lowers with other brands of uppers.
     
  10. tomykay12

    tomykay12 New Member

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    That, exactly was my concern

    Wondering about compatability between different manufacturers, though milspec should be milspec.... my lower is a s&w, and the PSA upper fits just fine. Just curious here, tk
     
  11. icallshotgun88

    icallshotgun88 New Member

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    I've done it without ever having a problem.

    But as I think about it you could POSSIBLY have a cycling problem..

    For instance if you're running a 20" rifle length upper with a really lightweight buffer..
    And then you switch to a 14.5" carbine length system, you might find you're cycling too fast..

    In this case you could keep a heavier buffer around..

    This is just an example and may not be what you're doing...just saying that it's possibel


    Sent from my iPhone using Firearms Talk
     
    Last edited: Jun 27, 2014