Guns, Burst and Crits: Tips?

[Marywn]

I have basically a class that gives me improved critical focus and deal a sizable amount of damage with crits, any items or magic items that will help me deal more crits or increase my overall damage?

[PraxisVetli]

An item made from Kaorti Resin has a x4 crit multiplier.

[Zaq]

Get an increased crit range somehow? There’s your basic Improved Critical and equivalents. Depending on the specifics, there’s also those old unupdated 3.0 PrCs that offer an expanded crit range that explicitly stacks with Improved Crit (disciple of Dispater, in BoVD, is the usual go-to; there’s also a somewhat more legally ambiguous psionic one lurking somewhere on the WotC web archives, but it arguably got nixed with the general 3.0-to-3.5 psionics update).

Of course, more attacks = more chances to crit, so whirling frenzy, haste, Rapid Shot, TWF (size permitting), and anything else that grants extra attacks is worth your attention.

If the weapon in question can be finagled into counting as a bow, the ranger spell hunter’s mercy grants an auto-crit, but it can’t be applied to just any weapon. The cleric spell surge of fortune grants an automatic nat 20, but as a 5th level spell, it’s not trivial to get on tap.

[tyckspoon]

Flat damage bonuses usually get multiplied by criticals, so although I wouldn't normally recommend them things like Weapon Specialization and Ranged Weapon Mastery can multiply up into satisfyingly large crit numbers (if you're optimizing for attacks per round, they also add up in general DPS for more benefit than one-big-hit styles get from them.) Getting a stat added to damage is helpful, if you don't already have one, via something like Targeteer variant fighter or the Hit-and-run Fighter ACF. The Collision weapon property is a standby here, being a nice chunky +5 extra damage that can go on either the gun (well, 'bow', but I assume any setting with guns will allow enchanted guns to transfer properties to bullets the way bows/crossbows/slings do to their ammunition) or on a set of bullets.