5.56 NATO vs. .223 Rem.: What's the Difference?
Many popular AR-15 rifles on the market are chambered in 5.56 NATO or .223 Rem. Externally, both rounds look exactly the same, but there are some critical differences between the two.
Since 1961, the O.F. (Oscar Frederick) Mossberg company has sold more than 11 million of its Model 500 pump-action shotguns, making it the most popular shotgun of all time, if not one of the most sold guns in any category, period.