Tesla Boom Stick

You create a floating firearm convulsing of electricity that lasts for the duration of the spell or concentration is lost. When you cast the spell, you can make a ranged spell attack against a creature within 60 feet of the firearm. On a hit, the target takes lightning damage equal to 1d6 + your spellcasting ability modifier.

As a bonus action on your turn you can repeat the attack against a creature within range. 

At Higher Levels. When you cast this spell using a spell slot of 2nd level or above, the damage increases by 1d6 (2nd is 2d6, 3rd is 3d6, 4th is 4d6, 5th is 5d6).