Well I had my own AR 15 in 80 but was really a M16. Yes I would love for one to ask me how.
The new AR 15 Jams even the M4 M16 troops are complaining, that it's Junk, while in Fire fights Marines have complained about the stopping
power of the 5.56 round at a 100M! Remember 2.23 and 5.56 not the same.
http://www.thegunzone.com/556v223.html
5.56 has a thicker case web, resulting in less internal capacity. The primer pocket is crimped. Its generally loaded with 55gr, 62gr, or heavier
bullets resulting in a longer COL.
.223 is generally loaded with bullets 55gr and under resulting in a shorter COL.
Those are the only differences in the cartridges, and there is lots of bogus hyperbole out there. The EXTERNAL case dimensions are identical
and anyone who says otherwise better pick up a reloading manual and get educated. Pick up a caliper and measure an unfired .223 and unfired
5.56 and they will be the same outside, save manufacturing tolerances. There are no-notations about the "neck" or any other part of the case
people make assumptions about, other than less-internal-capacity. As Hornady 7th offers a minimal bit of history on the subject, below the
actual case dimensions.
The danger lies in the CHAMBER of the gun. A gun chambered for .223 generally will have a shorter throat which lends itself to the short light
bullets. If you try and chamber a 5.56 with a long 62gr or heavier bullet, it may jam itself against the rifling upon chambering resulting in spiked
pressure above normal/safe levels. However, this is simply a function of a long COL because of a bullet sticking further out of a case, and that's it!
If you reload you can seat any bullet out too long in any caliber and have the same problem.
Somehow, the above became misconstrewn a million different ways toward Sunday. The difference is in the COL vs. the throat (leade) of the barrel....
not the neck or anything else. 5.56 GUNS will be cut to accomodate 5.56 ammo with long bullets, which means any .223/5.56 AMMO will be safe
in said 5.56 GUN. .223 GUNS MAY OR MAY NOT have the rifling cut short far enough from the chamber to fire bullets with a longer COL, and there
are few ways to find this out including a chamber casting.
Even Marines are picking up AK 7.62 and using them instead of their own Assault Rifles, Google you'll see many Pages on this topic.
For police Work there's nothing like using a Shot-Gun, 3" OOO Copper coated Mag or Rifled slugs.
With a telescopic butt and CCO as a 9 shoot extension Kite for 2 3/4".