There were zero facts given in my post. Those were all questions.
Clearly.. So I'll go out on a limb and say that one is a higher-energy, heavier-bullet version of the other. 5.56 NATO ammo needs the corresponding chamber and gas system. So perhaps your point is that 5.56 NATO ARs and ammo are unavailable to the general populace?.. Nope:
https://www.cheaperthandirt.com/search.do?query=5.56 nato&sku_instock_b=true -- freely available, just as the .223. Of course, with .223 Remington being a lower-performance version of the 5.56 NATO, one can own a 5.56 AR-15 and use .223 ammo. Which changes nothing, as 5.56 NATO cartridges are freely available as well.
Try me.
Wrong. The weapon was named ArmaLite AR-15 (.223 cartridges), a successor to the ArmaLite AR-10 (7.62 NATO), and was primarily an assault rifle, designed as an AR and approved as shoulder weapon for Vietnam -- a war fought primarily with assault rifles:
https://assets.documentcloud.org/documents/2859676/ARPA-AR-15.pdf
So yes, ArmaLite AR-15 was an
assault rifle by design and by designation. The army wanted higher-power rounds, though, so enter the M16. Moving on..
So, the original ArmaLite AR-15 design was really unsuitable for the militaries? Nope, it passed its mil tests, as noted in the document above. And, shockingly enough, a military AR is what Colt originally sold it for:
Moving on.
No, fullty-automatic does not mean 'several rounds at each pull of the trigger' -- that's burst mode; fully-automatic means 'the entire clip at one pull of the trigger' -- a mode-of-use effectively avoided by the troops for apparent reasons.
The original ArmaLite AR-15 was a select-fire assault rifle -- it was just as fully-automatic as the M16 modification. The "civilian" lineup (haha, a civilian assault rifle, how original), as already established, has presently models that use 5.56 NATO cartridges, and cannot shoot in full-auto, but so cannot various M16 modifications which are S-1-3. And now, I have to ask you the same questions I asked monegames above at the some point in our conversation: are you aware how the different firing modes of ARs are used in combat? And why a burst-mode M16 can effectively act as a semi-auto?
Does it need to be active duty?