the tiger was build for space-superiority like the aurora.. so please drop the idea of heavy weaps... but maybe we turn that turret into some chaingun-like primary...
I didn't mean "heavy" as in huge damage. But a decent damage, a few hundred rounds and a high firerate. And since it's a railgun, it could have a high subsys damage. So it's not overpowering because of the limited ammo, and not really dreadful when it comes to pure damage. But would be usefull still when strafing those dilgari warships. And using short controlled bursts to disarm them 
And give it a "huge" flag so the AI don't go wasting those ammo on 'roids.
Though a chaingun would still be one helluva destructive weapon in space, so there wouln't be much difference... But calling it a railgun lets us put some cool trails on those shots 
Was there a heavy fighter in the times of the Tiger? Im thinking Tiger was more of a multipurpose fighter, like the Aurora is (it has been used effectively against large targets more often than not).
I objected against the term of a "railgun" cause we already have weaps like this mounted on the Olympus and Warlock... adn there they serve primarly as AC guns...(no olympus I'd ingame used it for something different yet)
and we could use an high energy drain for that chaingun so it does not become too destructive... maybe it fires 400 rounds/sec but the tiger's generators can't support firing for longer that 5 secs
to fighters in the "Tiger time":
The Mitchell-Hyundyne SA-18 Tiger Starfury was the first of a new evolutionary line of space fighters, conceptual ancestor of the Nova and Aurora Starfuries.
This light interceptor was one of the protagonists of the Dilgar war: compact, nimble and heavily armed, was a real match for the Dilgar's Thorun fighters, and gave a significant contribution to the victory.
I too would put the tiger into an interceptor/all rounder roll but would leave it out of capship combat... what we have of the dilgar navy up until now is the Sekhmet which is nothing more than an support cruiser same as a midwinter....
and if you have send fighters against it in any mission you have to know that it is taking you fighters really quick if not stormed with masses...
you may try "Sword of the Empire" I'm going to post tomorrow (although I'm using Aurora Mk I. to replace the missing tigers) to see what's my point