Didn't the last Star Wars movie have deathstar laser mounted to battleships and they were all going to shoot one planet somewhere in the galaxy - and they started with Corrisont which was on the other side of the galaxy. Would that be considered longest range?
Mixing up a couple movies. The planet-killer fleet never got to use their main guns. Starkiller Base did destroy planets in another star system, but none of them was Coruscant. The main planet was commonly mistaken for Coruscant, but that's due to bad communication with the audience. The laser splitting to hit individual planets in the same system being visible with the naked eye from anywhere in the galaxy also indicates Abrams has no idea how distance works.