OR, as I like to think of it, "HAV Ordnance Theorem".

TL;DR version: Large Blasters become primarily a repeating PLC, with heavy mortar and flak gun variants, while missiles get an AA-oriented lockon variant and a ballistic arc rocket artillery version.

Long version:

Large Blaster Theorem
Quite frankly, Large Blasters have always been a bit odd in my eyes, and generally been plagued by balance issues. Infantry players cry out against Large Blasters being the anti-infantry turret, as they have a hard time fighting back against HAVs. HAV pilots cry out against AV Large Blasters because they already have Rails and Missiles for AV duties, and Blasters tend to be quite limited in their AV usage.

So, how to fix? Well, it's simple. We make the base variant of the Large Blaster a gigantic repeating plasma cannon. This makes it a good area-suppression/-denial weapon against infantry (but not necessarily a direct "slayer" gun), and requires a degree of skill that is, IMO, a tad lacking in the current design. It also acts as an effective, short-ranged version of the Large Rails that is also anti-shield specialized.

Large Blaster Turret, base variant
As described, a repeating Plasma Cannon turret. In terms of mechanics, think of the lovechild between a Large Rail and a Kubo's PLC. In terms of actual damage, no it would not use that as the baseline. Don't be stupid.

Large Blaster Turret, Scattered variant
Take the shotgun. Turn it into a giant-ass vehicle turret. Congratulations, you have the Scattered Large Blaster Turret. The goal of this variant is to function as an Anti-Aircraft Artillery piece. Note that for balance purposes, it should have very high heat generation, to prevent it from being spammed at infantry, and a fairly large reticle; the goal is to blast a dropship with dozens of small "pellets" that add up to deal lots of damage.

Note that this would obviously require very careful balance- however, it would be a great way to start giving HAVs a more defined role in the current framework of DUST.

Large Blaster Turret, Compressed variant
Take the base version. Dial up the direct and splash damage, make it have a big splash radius. Give it an incredibly slow RoF, large arc, and long time-to-live on the projectile. Then, give the turret a very high elevation angle. BOOM. You now have a gigantic plasma mortar system.

Artillery is sorely lacking in DUST right now, and IMO it would be quite beneficial to have dedicated artillery vehicles as a supplement to orbital support (or replacement, if there's no pilots on standby).

Large Missile Theorem
Large Missiles are currently pretty good, IMO... but they definitely have a lot of room for some interesting variants. Let's get to it:

Large Missile Turret, Guided variant
Giant-ass Swarms. Balanced appropriately, of course. The goal here is to provide another AAA option, for variety and flexibility. An HAV with a Guided Large Missile Turret would be the equivalent of a mobile SAM system.

Large Missile Turret, Cycled variant
You know the Compressed Large Blaster I mentioned above? Yeah, same principle. High blast radius, moderate blast damage, moderate impact damage, high capacity, high arc, moderate RoF.

Basically, you just turned your missile tank into a Multiple Launch Rocket System. Or in other words, heavy rocket artillery. Pretty awesome, huh?

Indirect Fire Theorem, Expanded
So, why should HAVs get indirect fire turrets? Won't they just sit in the redline like a bunch of sissy little girls? That might happen, yes.

However, in order for these weapons to work as artillery, you really need to have spotters on the ground to tell you that something is there. There is a requirement for great skill to properly adjust for range, arc, and travel time. Moreover, there's an element of teamwork/squadplay, as for best results you have to have somebody to tell you "hey, there's reds here", and to tell you "hey, you just missed by the whole map, you suck" when you miss, and "hey, you just wiped out half their team, that was badass" when you nail it.

Anti-Aircraft Artillery Theorem, Expanded
Derpship pilots are likely to crucify me for this, but I do have some ideas about small turrets, and I want to start with HAVs for vehicle rework concepts due to their greater accessibility to regular players (it's easier to drive a tank than fly a dropship).

That said, viable AAA turrets are a good idea because it provides an interesting role for HAV pilots, and possibilities for good counterplay mechanics between ground forces and air support (specifically HAVs vs DS/ADS). More HAVs also means more targets on the ground that are likely attracting more attention than your derpships, thus diluting AV fire.

So, thoughts?