.223Rem vs. 5.56 vs. 5.56x45 Whats the difference?

T

taco

New member
What exactly is the difference between these caliber designations?

I think .223Rem is the commercial load, 5.56 is the NATO military load with pressure/velocity higher than commercial load and 5.56x45 is same as .223Rem. I assume all three has same dimensions. Also, if the 5.56 is loaded to higher pressure/velocity than commercial, how much faster/more pressure does it generate?

Anybody here know the real story?
 
More specifically 5.56 NATO is the NATO round. I believe it is just a military designation for .223 Rem., because I've seen people shoot .223 Rem.'s out of 5.56 NATO guns. I think there is another one, 5.56*39mm, or something like that, that is different from the others. I may have gotten some things confused though.
 
scouter27:

I think you are thinking about the 5.45x39 Russian ammo. This is the cartridge that was developed with AK-74.
 
I think 5.56x45 is the full "discription" of the round, the 45 is the cases length, in millimeters. Just like .308 Winchester is 7.62 NATO, and 7.62x51. But I have been known, on veeeery rare occations, to be wrong! LOL
 
"Just like .308 Winchester is 7.62 NATO, and 7.62x51. But I have been known, on veeeery rare occations, to be wrong! LOL"

Actually, .308 Win has a different chamber pressure than the 7.62 NATO round. I won't hazard to guess which one it is, though, because I don't want it to be another rare occasion! ;)
 
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