Actually, i don't even know how you would controll the trajectory of a singularity? As in, what is stopping a targeted ship from simply turning away from it? At least missiles can trach a target, and beam weapons are instantaneous. |
First, beam weapons aren't instantaneous.

Thats a good question. By the point you've researched black hole guns, though, you've pretty much crossed the line between science fiction and fantasy anyways.
My guess is that it's a combination of a hyperdrive assisted launch and whatever extra dimensional stuff they're messing about with to get stuff like HD spike drivers...
Plus, I imagine the target would be pulled in via the gravitational field, too!

But, even with the lower tech mass drivers, consider the following:
1)The distances are measured in light seconds, but given relativistic speeds, thats not particularily long to toss a tiny piece of metal at relativistic speeds
2)Spacecraft accelerate very slowly, and if they want to avoid relativistic effects, they aren't travelling particularily fast when not using hyperdrive
3)Some of the mass drivers are supposed to be hyperdrive assisted, meaning that they'll be moving significantly faster than light
4)The early mass drivers at least are (according to the tech descriptions) firing like machine guns, meaning that their target is feeling the equivalent of a micrometeorite storm
Turning away from mass driver weaponry is as likely as dodging a laser, in that sense. Not too easy, though I suppose when you're a light second away, there's room to dodge lasers, too.