Well, i think Heavy Autocannons should be Replaced by good old HEAVY FCKN CANNONS.
You know, HEAVY CANNONS. The Thing with BIG Barrels that shoot BIG grenade like things - possibly with nukes attached to them - at Other peoples ships. And Yes Cannons work in space ,expanding gas is expanding gas. How you make it expand is a matter for the handvavium to discuss.
You could also do rails guns. Railsguns are back in sci-fi after the rather sudden demise of lasers and Energy Weapons.
Autocannons come with the problem that the bullet can't be too big, or the whole rapid fire thing won't be doable anymore. So in big honking spaceship combat they are like pea shooters, yes big pea shooters but still pea shooters in comparison to what is possible.
Instead of having virtualy EVERY major tec ship fire bullet storms of peas id like some REALY HoNKING BIG FAT CANNONS that will GUT the target and instead of doing lots of small holes do ONE BIG FAT hole, running trough the ship.
TEC Combat simply looks... unspectacular. Itrs boring. Steady yes, but boring.
BORING YOU HEAR?!
