In life, strive to take the high road....It offers a better field of fire.
"Robo is right" Fuzzball
then you get to the propritary cartridges like Lazerroni.
He bases his names off the groove daimeter.
Like the 7.21 Tomahawk is a 7mm caliber (.284")
The 7.82 PATRIOT is a 7.62mm (.308")