I don't think English is his first language, even though it says he's from Colorado. Either that, or he's un-smart (only non-insulting way I can say it).
Your user name? 357mm? .357's (as in the .357 magnum) aren't measured in mm, that's an INCH measurement.
357mm is over 14 inches. That's not exactly a carrying caliber.
Ron M. ('59 is my birth year)