Dead Shot (Ex): At 7th level, as a full-round action, the gunslinger can take careful aim and pool all of her attack potential into a single, deadly shot. When she does this, she shoots the firearm at a single target, but makes as many attack rolls as she can, based on her base attack bonus. She makes the attack rolls in order from highest bonus to lowest, as if she were making a full attack. If any of the attack rolls hit the target, the gunslinger’s single attack is considered to have hit. For each additional successful attack roll beyond the first, the gunslinger increases the damage of the shot by the base damage dice of the firearm. For instance, if a 7th-level gunslinger firing a musket hits with both attacks, she does 2d12 points of damage with the shot, instead of 1d12 points of damage, before adding any damage modifiers. Precision damage and extra damage from weapon special abilities (such as flaming) are added with damage modifiers and are not increased by this deed. If one or more rolls are critical threats, she confirms the critical once using her highest base attack bonus –5. For each critical threat beyond the first, she reduces this penalty by 1 (to a maximum of 0). The gunslinger only misfires on a dead shot if all the attack rolls are misfires. She cannot perform this deed with a blunderbuss or other scatter weapon when attacking creatures in a cone. The gunslinger must spend 1 grit point to perform this deed.
And as a machinesmith, I have an analyzer with True Strike as a use-activated spell-like ability :
You gain temporary, intuitive insight into the immediate future during your next attack. Your next single attack roll (if it is made before the end of the next round) gains a +20 insight bonus. Additionally, you are not affected by the miss chance that applies to attackers trying to strike a concealed target.
Ture Strike and Dead Shot used together would be a very cool combo, but I don't know if true strike would only affect my first attack roll when rolling for dead shot, or all of them.