01-09-2020, 08:29 PM
Don't know if this will help, but ...
https://en.wikipedia.org/wiki/FN_5.7×28mm
Hyperspeed flyweight bullets ... those aren't known for accuracy, and they all turn into flyers when they go subsonic. Maybe they were going for the reduced recoil, who knows? I suppose it was mostly done in hopes of landing huge military contracts. Meanwhile the good ol' nine has been around for about a hundred years, now, hasn't it?