I don't know anything about the hunting regulations in WV, (where that "old mountain man" is from) bearcreek, but I see you claim "N Idaho" is
your Location. It's against the law to hunt big game (except for mountain lions or legally-trapped gray wolves with
ANY rimfire rifle or rimfire handgun in Idaho. It's spelled out right there in black and white on page 100 of the "Idaho Big Game 2022 Seasons & Rules" book.
I won't be drawn into an argument about whether or not it's ethical to hunt black bears (or any other big game) with a 5mm rimfire either. Hunting black bears with a rimfire is
against the law in Idaho. Period.