General Discussion
In reply to the discussion: One Photograph, Two Bullets, And 26 Reasons We Need To Take Action For Newtown, Connecticut [View all]farminator3000
(2,117 posts)History
The .223 Remington (5.56x45mm) is a cartridge that is ballistically in-between its predecessors, the .222 Remington, and the .222 Remington Magnum. The 223/5.56x45 was developed to fit the action length of the new M16 service rifle. The 223/5.56mm quickly became popular as a civilian cartridge because of the availability of brass, and the chambering of commercial varmint rifles in that caliber. Shortly after military acceptance of the M16, the semi-automatic version, the AR-15 became available, making the .223 cartridge even more popular. As of January 2013, after political discussion of a possible assault weapons bans, there is currently a shortage of .223 ammo in the United States
http://en.wikipedia.org/wiki/.223_Remington
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After seeing the ArmaLite AR-10, they discussed their desire for a
scaled-down model. ArmaLite engineers Jim Sullivan and Bob Fremont scaled down the
AR-10 to fit the hot varmint cartridge of the day, the .222 Remington. During some
preliminary military testing, it was decided that the .222 Rem wasn't quite powerful
enough. Though the .222 Remington Magnum existed and had the power they were
looking for, the severe shoulder angle would have prevented positive feeding in a semiauto,
and so it was decided that the best solution was to lengthen the .222 Rem case. The
result was the 5.56×45mm cartridge, designed by G. A. Gustafson, which Remington
released commercially as the .223 Remington. This cartridge has virtually identical
ballistics as the .222 Mag and, over time, the wide availability of .223 guns and ammo
has lead to the demise of the .222 and .222 Mag cartridges.
The AR15 was initially adopted by the Air Force, but the need for rifles for soldiers
heading to Vietnam gave the "medium-power cartridge" supporters an opening and the
AR15 rifle was hastily procured, initially as a one-time purchase. Continued problems
with the M14 program lead to the official adoption of the AR15, which was given the US
military designation "M16."
http://ammo.ar15.com/project/AmmoOracle_061808.pdf