There's alot of things that could be changed to ONLY the guns numbers and stats to make things alot more understandable (and fun) for new players, while also (hopefully) increasing the competitive choices available for guns.
Let's start by having a look at the current guns we have, and what roles they fill:
Medium Guns:
Balloon damage:
Heavy Carronade (Short range)
Heavy Mortar (long range)
Armour damage:
Heavy Carronade (short range)
Heavy Mortar (Long range)
Hull damage:
Heavy Hwacha (Short range)
Heavy Flak (Long Range)
Component damage:
Heavy Hwacha (Short range)
Heavy Carronade (Short range)
Other:
And yes, hwacha has (significantly) longer effective range than the carronade, the mortar has longer range than the flak as well, and none of the guns do piercing damage so technically they aren't the best armour killers. There is a bit of generalization for the sake of brevity here, don't worry, the actual range is taking into account in the discussion.
Light Guns:
Balloon Damage:
Carronade (short range)
Flamethrower (short range)
Armour Damage:
Gatling gun(short range)
Mercury gun(long range)
Flamethrower(short range) (not the greatest, but fire has a decent armour damage ratio. and it's easy to get alot of stacks on it)
Hull Damage:
Scylla double mortar(short range)
Light flak (short range)
Artemis rocket launcher(long range)
Banshee (long range) (not a ton of damage but hey, it's all explosive)
Flamethrower (short range)
Component Damage:
Carronade(short range)
Mercury gun (long range)
Artemis (long range)
Gatling gun(short range)
Flamethrower (short range) (not so much damage but still disables them so eh)
Other:
Harpoon Gun(short range)
Mine Launcher (kinda counts as short range I guess?)
Flare Gun (short range (mostly due to inaccuracy))
So let's start making observations. First off there is no medium gun with long range component disabling ability (hwacha is medium effective range at best and even then can be dodged). There is also no medium gun that both does good damage vs. armour AND hull, but there are both long and short range versions for each seperate role. Ignoring for the moment how well each gun does at performing it's given role, these guns seem pretty balanced.
The first thing one may notice with light guns is that flamethrowers *seem* pretty much good against everything. Having used flamethrowers however, besides their range being prohibitive, I also find it questionable how much damage it actually does or does not do, as it does not seem to kill things (besides the balloon) nearly as quickly as it's damage ratio's would indicate. In short the flamethrower is probably not broken despite doing good damage to everything.
The second thing is that all balloon and component damaging skills are short range besides the Artemis, Mercury, and in medium the heavy mortar. Let's take a closer look at those guns.
The heavy mortar disables the balloon and damages the armour, the Mercury disables components and damages the armour, and the artemis damages the hull and disables components.
The mortar, while hard to use for new players, is problematic because it runs the enemy ship into the ground WHILE removing their armour. The Artemis won't do much damage besides disabling components until the armour is down, so that seems balanced. The Mercury on the other hand disables components (such as the engines and guns) AND removes the armour, and is thus also problematic.
The reason why these two guns are problematic is because they don't require as much teamplay (meaning combination with other guns/ships) as other guns do, because they essentially fill the role of two guns at once (a disabling gun and a damaging gun) without paying enough of a penalty at one of the two roles. The artemis is a good counter example of how a double role gun should work. It's nowhere near as good as the specialized guns in it's area, but it has the advantage that, when one of it's roles is no longer required, it's less of a waste of a firing arc compared to the more specialized guns.
Essentially, if a gun fullfills multiple roles with it's damage, it should pay a price for that, either being very ineffective at one of the roles, or being significantly less powerful (though obviously not useless) at both.
The banshee and flamethrower could be put in a seperate category for "firespreaders" short and long range, but the banshee is so ineffective at doing, well, anything at current, that it'd be inaccurate. Changing banshee to do a bit more explosive damage and having a slightly higher fire-starting chance would make it a great hybrid purpose gun for long range engagements, an alternative to the artemis, perhaps.
Speaking of the artemis, it is currently used only for it's very large firing arc (the exact firing arcs of the different guns should be more easily available information, since it's as important as the amount and type of damage being done when fitting a ship) as the mercury does it's job better at disabling and damaging ships at long range, and it's explosive damage doesn't come into play untill the hull armour is down. Add to that that the sniper and heavy mortar are the only guns good at removing armour from a long distance, and most armour damage has at least a "long" short range, getting that sniper on a ship is simply required for a long-range setup.
So how do we change the artemis/mercury to be more used/less frustrating? well quite simply we can look at the roles and what is required. Currently there are 2 light guns fullfilling the long range component disabling role (3 if you count the banshee), and only 1 fullfilling the armour removing role. I'd suggest specializing the mercury to taking out armour, and the artemis a bit more to taking out components at long range. Not only does the artemis have more counterplay as it's a missile and thus easier to see coming and dodge, you will have to make choices when making a long-range build whether or not you're going for more damage, or more disable, rather than just having both (fairly similiar to short range, though short range should always be more damage as it's more dangerous and harder to keep multiple guns on target)
As for the heavy mortar... I'd say just straight up reduce the flechette damage a bit (or the size of the aoe), or reduces the ammo/fire-rate of the gun, it's not as much of an issue that it can damage the armour as well as the balloon, as the speed at which it can do it (and damage both at the same time).
I'd also make a case for the gatling gun to be more focussed on armour damage, as it's the only short ranged gun that's much good at it, and trying to hit specific components with it is just silly(besides we have the carronade for short range component disabling).
Heavy flak just needs to be more accurate, it feels like it's a long-range gun(and the arming time supports this), but it seems to have unnecesarilly high jitter as well as relatively slow missile speed and high drop-off (it's damage is fine, just trying to hit things with it could be less of a bitch with the lesmok being nerfed now)
Anyway I could probably keep going all day but I'd like to hear other people's thoughts on what I've had to say.