What Uppers fit?

Discussion in 'AR-15 Discussion' started by 1984cj, Sep 6, 2007.

  1. 1984cj

    1984cj New Member

    I am a recent addition to the Evil Black Rifle Club( and it IS evil, when I get it out my dog runs away in fear!). I know a little about them.
    I can shoot and field strip my AR but that is the end of my experience.
    I am much more familiar with M-14's, 1911A1's, M-79's, Rem 870's, M-60's and M2's.

    I know that you can get different style uppers for them.
    I currently have a 24" .223 heavy barrel and a flat top upper. Nice for varmint type shooting but not exactly Service Rifle competition or 3 Gun material.
    I would like to put either a 16, 18 or 20" upper on it. I want to end up with an accurate military appearing rifle/carbine that I can use in 3 gun or CMP matches.
    I want to stay with .223 or 5.56 NATO

    Do I have to buy a new bolt& charging handle or can I reuse my current one?
    Will all uppers ft my Eagle Arms lower receiver?
    Will M-16 uppers fit the AR15?
    I have read that firing 5.56 in .223 chambers causes an overpressure condition. Is this fact or fiction?
    Should I go with a .223 upper or a 5.56 upper?
    What should I expect to pay for a Complete upper?
    How about one w/o bolt and charging handle?
    Where would a good place to buy and upper be? Gun show? Auction Arms? Gunbroker?
    Anything that I forgot to ask that I should have?

  2. ARShooter

    ARShooter New Member

    It is better to use separate bolt and charging handle for each upper. The two pieces wear in together and can cause premature wear of both parts if swapped often. Upper and lowers interchange basically as long as it is non Colt parts they are interchangeable. Colts use different pins and require adaptors to work with non Colt parts. Since it is Eagle pretty much any upper will work. Using an M16 upper has some legal issues since the ATF sees it as once a machine gun always a machine gun. If you use an M16 upper do not use the bolt, get a AR15 bolt for it. Mechanically they will interchange. For service rifle get the 5.56 with a chrome bore. You can use 5.56 and .223 in a 5.56 but sometimes there can become sticking and it is about 10,000 psi more pressure in a 5.56 over .223. Uppers vary in price due to how you want one set up. www.adcofireams.com has a good selection of uppers. As for with out a bolt since the bolt is about $125 at shows I would say no less than that for a price reduction. Shop around for uppers I have bought from www.adcofirearms.com and www.rbprecision.com shop around I have had good luck with Rock River and Bushmaster rifles.
    Last edited: Sep 6, 2007

  3. bkt

    bkt New Member


    You shouldn't have to, but I recommend having a complete upper for every upper you own. As ARShooter says, the parts essentially "mate" together; don't break 'em up.

    In theory, yes. If the manufacturer adhered to MILSPECs, an upper from Rock River should fit fine with a DPMS lower, for example.

    I have read that Olympic Arms rifles do not play well with parts from other manufacturers.

    Can't say for certain, but I think so.

    Can't speak from experience, but others say it's fact.

    5.56. It eliminates any potential risk and most are chambered for that round, anyway.

    $450-$500, unless it has some slick gas piston setup or other neat features.

    No idea, sorry.

    I got my Stag upper from Legal Transfers out of New Hampshire. Google ar-15 and follow your nose with the first or second hit...
  4. jeepcreep927

    jeepcreep927 Active Member

    On so far. 5.56 chamber dimensions are different than .223. The "lead" is different therefore potentially causing problems if attempting to fire 5.56 ammo in a .223 chamber, but not vice versa. M16 uppers will fit any (mil spec) lower. There are no mechanical differences in the upper receivers what so ever.