The ship controls and contort subattomic energy flow from subspace, emerging in the ring.
I hope to do a illustration how the weapon works. For now imagin its a higher dimension gun, where the round nozel of the gun emerges into our space.
The energy released is dependant upon desired effect.
The larger the ring, the greater the instantaneous range, due to the greater 'lensing effect'. There is no dodging once fired, just hope the gunner is not as good.
These rings also serve as thrusters for manuevering the craft. After all engines, like guns, use and emit energy. Although it more or less uses ambiant energy around in normal space and manipulates it to 'swim' in normal space.
Often their equipment has dual purposes. (In the story I and still pondering doing, the first time a human complains about the lie Altronians are peaceful by pointing out all the guns on their ships. The Altronian has to pause and think, "Oh yeah! I been using the targeting so long for astronomy I forgot it can shoot!" Which states miles about their targeting technology at the same time about how rare it is for them to be challenged.)
Yeah Gate guns are one I really wanting to illustrate more.