[quote=Keyguyperson]
Exactly, the railgun weapon is completely impossible (unless you equip every projectile with an FTL drive). Honestly, in a far future setting where corvette class ships have the power to violate the laws of physics simply using the "MOAR POWAH" philosophy, we would see nuclear bombs as primitive devices. Antimatter weapons would rule the battlefield, a single bomb taking out an entire continent. There would be railguns that fire projectiles that contain antimatter within them, taking out starships with a single hit. To take out the shields though? Just good old railguns (provided the shields are at least somewhat similar to literally every other sci-fi energy shield). Just a thought here, what if the shields took the mass of physical attacks and the energy of, well, energy attacks and used that to power the system? There wouldn't be any "Shields at 20%!" the shield core would simply short out after a sufficient number of attacks were thrown at it. You could even take it a step further and have the attacks used to power the entire ship, so when the shield goes down, the entire vessel is disabled or destroyed, depending on how dramatic you want it to be. Going with that would give you an excuse to use projectile weapons over energy weapons, as mass converts to absolutely ludicrous amounts of energy. That's why we won't get teleporters for millions of years, converting a human body into energy would probably blow up the entire planet.Also, it would be nice if you would keep me updated, I am most certainly interested in this!
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Antimatter weapons require reliable containment methods to keep them from killing whatever it is that is carrying them. If these containment methods fail (either from an error in their design or by the malicious strike of a foe's accurate laser fire), which will probably be an electromagnetic field, then the antimatter reacts with matter, explodes and probably causes a chain reaction to occur within the vessel that is carrying them. I don't know about you, but I wouldn't want a single weapon like that on-board my multi-billion dollar war vessel, let alone 30 of them. 

Fusion or fission munitions, specifically shaped charges (l[url=http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion]) provide longer range as well as a safer alternative, since a fusion or fission missile isn't going to violently explode if a random projectile comes to say hello. They're also cheaper, and thus could be spammed more. Not saying AM weaponry is useless, but they're far from the god-tier weapons sci-fi likes to portray them as.

For space engagements, I'd ditch the railguns. While useful at close range (and in other roles), they're badly gimped by space's sheer vastness. I'd go with an x-ray laser or gamma ray laser, or a charged/neutral particle accelerator weapon, for long-range engagements.