A 10 meter long magnetic tube can propel a small projectile to nearly 4 times the speed of sound before it exits the "barrel". Its been done earthside, with the huge problem being that you need to maintain a vacuum to achieve it. That's the basics behind NASA's Mass Driver delivery system (being researched). Just think that with mere magnets we can propel a passenger train weighing TONS and TONS of kilos to very high speeds (bullet trains)... and without a vacuum! And how fast are the bullet trains that are being designed to work in vacuum travel? FAST. Damn fast.
In space, having vacuum for granted, you could make a machine gun with those principles (in fact, if it hasnt been already designed and tested by the US gov's "black programs" id be VERY surprised!). You could also have weapons firing slower projectiles to cause more damage to the surface of the target.. a high speed projectile in space is more likely to make a hole in one side and another on the other side since it doesnt have time to transfer all its kinetic energy to the target.. and not much damage may be done, but a relatively slow flying projectile (400mph?) would be able to impact and fully x-fer its kinetic E and create some serious damage. It all depends on what you want to do with the weapon.
"Gunpowder would ingite perfectly well in a vacuum or underwater - even the ancient blackpowder. That is an advantage of having an oxidizer as a part of a mix.
Actually, gunpowder ignites inside the shell/barrel anyway, so it couldn't care less if there is vacuum outside or not."
Yes, but the gas pressure on the barrel would dissipate at a much faster rate than on earth (where you fire stuff under 1 atmosphere of pressure) and thus have less power to propel the projectile. Besides, a magnet does it better and far cheaper.
"A big ship with unlimited computing power and ammo will have a huge advantage over a small "fighter"."
Not if that fighter has missiles. Or if that fighter has 2 dozen others like him firing missiles at the cap ship at the same time.
"Any fighter would have to shoot from extreme distances and the large ship would either easily evade dense stream of dumb progectiles or "shoot down" scattered ones with it's own bullets."
Large ships have larger inertias to overcome, no matter how poweful an engine it has.Besides, a spray of bullets is hard to evade with such big vessels.. quite a few are likely to hit. A fighter on the other hand would be able to "jink" to avoid defensive fire and get close to the cap ship (though I doubt getting close to a cap ship would be something a fighter would want to do hehe) . I would also consider shooting down a bullet with another bullet to be not only extremely improbable, but also impractical. A missile, being large and having an engine perhaps, but not a bullet.
"An x-ray laser nuclear warhead/torpedo launched from far away and detonated miles from the target to direct a pack of light-speed X-ray beams at the target would be a logical device."
Too expensive imo. Remember your best weapons are done by the lowest bidder.
Magnetic rail guns do not create recoil. Magnets do all the work.
