The modified TR-116 rifle

"Field of Fire". After two murders on Deep Space 9 involving a chemical projectile weapon that was fired from close range but without causing powder burns on the victims' clothing, Chief O'Brien has an epiphany about how the killer did it. He demonstrates to Ezri Dax and Odo a modification to the prototype TR-116 semiautomatic rifle used in the murders: a miniature transporter that beams the bullet from the shooter's location to nearby its target after the bullet is fired, paired with a targeting headset that lets the shooter target any location, anywhere on the station.

Example of:
Fantastic Firearms