# I didn't know this



## toma (Oct 10, 2007)

I just assumed it was the same as with 223 versus 556 but not so.


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## WAReilly (Jun 2, 2014)

Very interesting. I didn't realize this either.


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## welldoya (Oct 5, 2007)

Same thing with .223 and 5.56. Slightly different. You can fire a .223 in a rifle stamped 5.56 but not recommended that you fire a 5.56 in a rifle stamped .223.
5.56 is loaded to higher pressures and is slightly longer.


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## Bodupp (Oct 3, 2007)

Supwiddat? Are military style rifles that are offered to the general public, like the AR-10 and M14, stamped .308 or 7.62x51?


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## Bravo87 (Jun 19, 2014)

News to me. Thanks for the info


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## FlFrayedKnot (Feb 15, 2009)

IIRC, my loading resources showed different rim thicknesses. I have tried 7.62x51 in two different .308's, one a single shot and one bolt, and neither would extract the NATO brass. Some have reported no issues, so seems to be really rifle based.


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## John B. (Oct 2, 2007)

Ran some ZQ1 7.62x51 through my Browning BAR .308, surprisingly it shot sub moa at 100 yards.


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## FlFrayedKnot (Feb 15, 2009)

John B. said:


> Ran some ZQ1 7.62x51 through my Browning BAR .308, surprisingly it shot sub moa at 100 yards.


Proof of you get what you pay for, and makes sense since Browning was responsible for the BAR they would ensure it would feed both. Always loved Brownings, like a man on a sirloin diet loves some porterhouse!


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## John B. (Oct 2, 2007)

FlFrayedKnot said:


> Proof of you get what you pay for, and makes sense since Browning was responsible for the BAR they would ensure it would feed both. Always loved Brownings, like a man on a sirloin diet loves some porterhouse!


Yep. It shot a hell of a tighter group than the Hornady American Whitetail and the Federal Fusion MSR I had... not bad for some stuff that's $10/box. Just wish it wasn't FMJ!


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## floorguy (Jul 22, 2011)

My rock river AR(lar-8) shoots both


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## HappyTime (Dec 31, 2013)

There has always been mixed reviews on this subject. Talking to gunsmiths who say it doesn't matter with modern guns in good shape, and internet searches say it's a no-no??


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