an idea for a non falling bullet, has been made?

[White Owl]

Don't most of these guns in WWII fighters fire supersonic rounds? I think they do... but I know almost nothing about ballistics and machine gun technology and all that kind of stuff so I'm probably wrong.

Anyway, if they're supersonic then that adds a whole new level of complication to your plan, because the effects of supersonic aerodynamics can be unusual and unintuitive. And of course you need to figure out how to keep your bullet stable as it decelerates from supersonic to subsonic speeds.

It's probably a better idea to stick to good old-fashioned rifling while we wait for our awesome fat laza beamz.