Masterwork Guns (3.5e Variant Rule)

Masterwork Guns
The way masterworking rules in DnD function is fairly dull. No attempt is made to make masterworking in any way interesting, given that it's only a small bonus to attack rolls that you're likely to forget in a few levels, but even more damnably, a masterwork scythe gets the same benefits as a masterwork crossbow, which is patently silly. While the scope of that problem is beyond this particular rule, this aims to fix a sub-problem of this: the fact that masterwork guns are boring.

Everyone likes the idea of guns being something cool and awesome - and masterwork guns should be cooler and awesome-er than that. Additionally, the whole flavour of guns implies that they are unique works of craftsmanship as far as DnD is concerned - and thus, masterwork versions of such weapons shouldn't be simply a case of bigger numbers. This is exactly the problem this rule seeks to address, by making masterworking provide actual abilities for guns people actually care about.

A note on application
These rules were written with the following guns in mind: pistols, jezzails and blunderbusses. While these rules could be used with other firearms, check with your GM first to resolve any potentially-weird interactions.

The rules
A masterwork gun no longer receives the +1 enhancement bonus to attack rolls. Instead, at the time of masterworking, select one of the following benefits to apply to the gun in question. A gun can only be masterworked once.

Incendiary
With an internal tank of alchemist's fire or some similar substance, this gun's ammunition ignites as it is fired.

A gun with this ability deals fire damage instead of its normal damage type. Additionally, anything that is struck by a shot from such a weapon catches on fire.

Penetrating
Due to a redesign of the firing mechanism and the barrel, the gun can fire much larger pieces of ammunition, with a much larger payload of powder, allowing its shots to 'punch' through many targets at once.

This masterwork ability can only be applied to a gun which makes attack rolls. As a full-round action, the wielder of this weapon can make a special attack. Instead of making an attack roll, the user generates a 5ft-wide, one-ranged-increment long line-shaped burst. Anything in the area is dealt the gun's damage, with a Reflex save (DC 10 + 1/2 the firer's BAB + the firer's Dexterity modifier) for half damage. If the firer uses a different ability score to calculate ranged attack rolls, they can use that ability score modifier instead of Dexterity to calculate this DC. If the gun has an enhancement bonus on attack and damage rolls, apply this enhancement bonus to this DC.

Precise
''The gun has been made to fire straighter. This can include sights, or might just be a better barrel design or something.''

When making attack rolls with the gun, the firer is considered to have the Precise Shot feat. This can be used to qualify for other feats, but these feats can only be used with this gun, or any other gun with this masterwork ability.

Ruinous
With special modifications and unusual ammunition, this gun is designed to break objects rather than people.

The gun ignores an amount of hardness equal to the firer's BAB. Additionally, if an attack from a gun misses a target wearing armour or carrying a shield, but misses by an amount equal to or less than the benefits provided by either, the firer can choose to have the gun deal its damage to the armour or shield of their intended target.