Not only are these two rounds often interchangeable and able
to be shot from the same gun, their history is entwined with each other. In
fact, the 5.56 NATO round didn’t come about until after the .223 was produced.
In 1957, Fairchild Industries set about to create and new lightweight combat
rifle. They were commissioned, along with several other groups of engineers, by
the US Continental Army Command (CONARC) with a set of specific criteria that
the gun and round had to meet. These parameters included:
Able to exceed supersonic speeds at 500 yards
Rifle itself could only weigh 6 lbs.
Able to penetrate both a steel helmet and .135”
steel plate at 500 yards.
Magazine capacity of at least 20 rounds.
These specifications came as a result of the 7.62 NATO round
being deemed has having too much power to be carried by infantry. In May of
1957, Eugene Stoner shot the first AR 15 design to CONARC. Through further
developments, the AR-15 was transformed into the M16 rifle that is still the
standard rifle for most of the American Armed forces.
The difference between the two rounds? Pressure. The outside
case dimensions are essentially the exact same for both rounds. However, with
the military having different pressure testing procedures than the civilian
institute of SAAMI, the two rounds often are loaded to different
specifications. Simply put, the .223 to generally used by civilians while 5.56
NATO is often found in military surplus buys.
Each box contains 500+ once fired brass shell casings. May contain some 5.56 mixed with 223.
This is unprocessed brass sourced from commercial shooting ranges. It has not been cleaned or resized and still contains the spent primer.
This brass contains different manufacturer's headstamps. It is recommended that all brass be inspected prior to being reloaded and fired.