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Author Topic: AR -- larger caliber upper on a 5.56 lower?  (Read 8380 times)

ScottyT

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AR -- larger caliber upper on a 5.56 lower?
« on: October 17, 2008, 05:34:53 pm »
Please feel free to smack me around a little as I am a total AR n00b.

I was wondering what larger caliber uppers would be compatible with my 5.56 lower.

Isn't this what the .50 Beowulf and 6.5 Grendel were developed for?  They look cool, but I don't like the idea of only one source for ammunition.

Are there any other options?
"I seek not for power, but to pull it down. I seek not for honor of the world, but for the glory of my God, and the freedom and welfare of my country." - Moroni

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    THE NORSEMAN

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    Re: AR -- larger caliber upper on a 5.56 lower?
    « Reply #1 on: October 17, 2008, 06:41:34 pm »
    Well there's also 6.8 SPC.

    With a standard AR there are 2 issues.

    1.  Mag well depth front to back.  The cartridge has to fit.  Just the way it is.

    2.  Round design.  The straight mag well doesn't lend its self very well to long(high capacity) magazines carrying rounds that have a lot of taper front to back very well(think of the AK mags for instance).  You'll notice a lot of folks with 7.62X39 uppers have mag troubles.  It pretty much inherent in the design.  Right where the mag goes from curved to straight it's physically prone to pinch and jam.
    « Last Edit: October 18, 2008, 12:14:43 am by THE NORSEMAN »
    This may be considered as the true palladium of liberty. . . . The right of self defence is the first law of nature: in most governments it has been the study of rulers to confine this right within the narrowest limits possible. Wherever standing armies are kept up, and the right of the people to keep and bear arms is, under any colour or pretext whatsoever, prohibited, liberty, if not already annihilated, is on the brink of destruction- St. George Tucker, Blackstone's Commentaries

    ScottyT

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    Re: AR -- larger caliber upper on a 5.56 lower?
    « Reply #2 on: October 17, 2008, 06:49:10 pm »
    I forgot about 6.8 SPC.  Thanks.

    Opinions on 6.8 SPC vs. 6.5 Grendel?
    "I seek not for power, but to pull it down. I seek not for honor of the world, but for the glory of my God, and the freedom and welfare of my country." - Moroni

    MikeGolf

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    Re: AR -- larger caliber upper on a 5.56 lower?
    « Reply #3 on: October 17, 2008, 06:57:05 pm »
    Just about any. Ive seen .50BMG uppers on them.

    ScottyT

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    Re: AR -- larger caliber upper on a 5.56 lower?
    « Reply #4 on: October 17, 2008, 07:06:33 pm »
    Just about any. Ive seen .50BMG uppers on them.

    I think I might have trouble feeding the .50 BMG through a magwell designed for 5.56...

    But I did not major in putting square pegs through round holes...    :P
    "I seek not for power, but to pull it down. I seek not for honor of the world, but for the glory of my God, and the freedom and welfare of my country." - Moroni

    JesseL

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    Re: AR -- larger caliber upper on a 5.56 lower?
    « Reply #5 on: October 17, 2008, 07:09:20 pm »
    There are a number of rounds based on the .223 cartridge family that have been necked up to run larger bullets in the AR-15 platform. 300 Whisper is one such that's pretty well known.

    There are also a few uppers built for the .223 WSSM & .243 WSSM. Then there's the .450 Busmaster and Remington is supposed to be rolling out a new round based on the .450 Bushmaster the .30 Remington AR.

    I really think that ammo availability will probably be an issue with almost very alternative chambering for the AR (with the exception of 7.62x39).
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    MikeGolf

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    Re: AR -- larger caliber upper on a 5.56 lower?
    « Reply #6 on: October 17, 2008, 07:54:52 pm »
    Quote
    But I did not major in putting square pegs through round holes... 
    These guys did.  www.watsonsweapons.com

    THE NORSEMAN

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    Re: AR -- larger caliber upper on a 5.56 lower?
    « Reply #7 on: October 17, 2008, 08:01:41 pm »
    If you don't mind a single shot there are several companies that make bolt action uppers in calibers that won't fit through the mag well.
    This may be considered as the true palladium of liberty. . . . The right of self defence is the first law of nature: in most governments it has been the study of rulers to confine this right within the narrowest limits possible. Wherever standing armies are kept up, and the right of the people to keep and bear arms is, under any colour or pretext whatsoever, prohibited, liberty, if not already annihilated, is on the brink of destruction- St. George Tucker, Blackstone's Commentaries

    ScottyT

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    Re: AR -- larger caliber upper on a 5.56 lower?
    « Reply #8 on: October 18, 2008, 02:24:36 am »
    ah single shot, got it!  Thanks for the edumacation!
    "I seek not for power, but to pull it down. I seek not for honor of the world, but for the glory of my God, and the freedom and welfare of my country." - Moroni

    mattitude

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    Re: AR -- larger caliber upper on a 5.56 lower?
    « Reply #9 on: October 18, 2008, 07:35:49 am »
    My first .50 BMG was a Watson's and for the price (at the time it was like 1200.00) it was the cheapest thing going.  But that was also the time when ammo was 119.00/100rds. loose in a can.  I have 50AE upper for my AR lower and it does work awesome.  The ammo is more available than the other big bores (.50 Beowulf, .458 SOCOM, .450 Bushmaster), cheaper and a better variety of projectiles.  If you reload, the components are cheaper for the AE round.
    North CarolinaMedically retired Air Force (17 years, 7 months & 25 days)

    txgho1911

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    Re: AR -- larger caliber upper on a 5.56 lower?
    « Reply #10 on: October 18, 2008, 07:47:35 pm »
    6.5 Ammo is in production by Wolf as well as through Alexander Arms.
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