If you have artificial gravity you have reactionless thrust engines. They require power, but have no exhaust.

Depending how sophisticated your grav plates, you may have to mount them on articulated frames or they may be able to produce assymetric fields for maneuver. (Or tiny vessels with one or two plates may need articulation while large vessels with many plates vary the intensity across the array for steering.)

If you want reaction engines that don't eat up a moon worth of fuel every trip, (our current reason we don't have constant thrust spaceships,) you need extreme exhaust speeds at about X-ray velocities and intensities, which means, who needs a gun? The drive engine is by far more dangerous than any projectile weapon you could mount on it.

If you want the aesthetics of a reaction drive, may I recommend a hybrid system in which grav plates in the exhaust system increase the apparent mass of the exhaust material so that the drives require less fuel and much less dangerous exhaust speeds? This allows kilograms of reaction mass to act like kilotons, and you aren't spraying inner systems with radiation and hot subatomic particals with every visit.