Why not regulate guns like cars, I hear the libs say. Well sure, with registration by VIN number to a specific person so that when convertibles are outlawed, the cops will know who has a convertible. But wait, there's more.
Your gun, once registered to you, would be usable in every state and territory of the US, and not just by you, but by whomever you loan it to.
It may be carried in whatever manner the carrier chooses.
Etc, etc. But don't forget the Federal input to the design process.
All guns would have a glove around the grip, pistol or otherwise, with retention straps that must be cinched up before the gun can be used. Failure to do so will result in a flashing icon and an annoying beep until you fasten your wrist strap.
The fancier sorts of semiautos will have a small camera on the top looking backwards to warn you if your thumb is about to get hit by the slide. Hyundai guns won't shoot if your thumb is in the wrong place.
Should the gun find itself in a zero-G situation, an all-enclosing air bag will deploy to prevent accidental firing. Large-caliber guns will have an additional airbag on the top of the frame which will deploy if the gun rotates more than 90 degrees after firing.
Long guns will have a pressure switch in the back of the stock that won't allow the gun to fire unless the stock is firmly against your shoulder. Or something.
Automatic Stability Control: If the shooter should pull the trigger several times in quick succession, the gun will automatically limit the rate of fire to one shot every 2 seconds.
When you empty a magazine, a panel on the back side of the gun will light up showing a "check Mag" message and icon. Every 200 rounds, the icon will read "service gun soon".
It will be illegal to remove your silencer although some people will replace the factory one with a less efficient one.
The police will be exempt from all of this.