The effect is more complicated than suggested in the in-game tooltip. In addition to letting the user hold the trigger down to charge a more damaging hit, it radically changes the base damage type of the Gamma gun.
Because the effect is non-trivial, refer to the damage/special section on the "Electrified gamma gun" and "Electrified Lorenzo's Artifact" infobox for information on changes. It adds electric damage.
Electric signal carrier antennae (1)