.222 Remington - Wikipedia
https://en.wikipedia.org/wiki/.222_Remington
WEBThe .222 Remington or 5.7×43mm (C.I.P), also known as the triple deuce, triple two, and treble two, is a centerfire rifle cartridge. Introduced in 1950, it was the first commercial rimless .22 (5.56 mm) cartridge made in the United States. As such, it was an entirely new design, without a parent case. [2]
DA: 38 PA: 33 MOZ Rank: 18