Let’s change the end: Never fire a round into the air for any other reason than shooting an actual target (e.g. trap shooting, waterfowl hunting). If you want to fire things in celebration, or for ceremony, use blanks. It’s what the Army does with the Old Guard around DC.

Basic firearm safety is effectively a laser beam theory (yes, parabolic arcs plus wind, etc. is more accurate). “Never point the weapon at anything you do not wish to destroy.” Don’t flag (point the business end of the gun at) your friends as a “joke”. Never look down the front end of a barrel (always inspect from the rear after disassembly.

Laser beam works well for most people as most concerns are relatively flat line in under 500 yards when working with most firearms. So just don’t shoot where you don’t have a known backstop.

I’ll end with the advice a prior-service (Vietnam) 82nd airborne guy gave me when he was doing firearms instruction. Paraphrased: “Always keep the weapon pointed at the ground. If you have an ND [negligent discharge] and you can’t tell me where the bullet hit, you’re off my range until you bring it to me.” He is a Texan, so there was some more, uh, colorful language in there. :)