The Gunslinger has a clear primary ability: Dexterity. The remaining scores depend on subclass and character concept.

Dexterity

Dexterity powers firearm attacks.

It also improves initiative, Armor Class in light armor, Dexterity saving throws, Acrobatics, and Sleight of Hand.

This makes it the most efficient ability in the class.

Constitution

Constitution increases hit points.

The Gunslinger uses a d8 Hit Die and can attract attention once firearm damage becomes threatening.

A good Constitution score provides more room for mistakes and close-range pressure.

Charisma

Charisma is one of the Gunslinger's saving throw proficiencies.

It also supports Deception, Intimidation, and Persuasion, all natural skills for several Gunslinger concepts.

Certain subclasses may value it more heavily.

It does not replace Dexterity for the base firearm chassis.

Wisdom

Wisdom supports Perception and Insight.

A sharpshooter, scout, or bounty-hunter concept may value awareness highly.

Intelligence

Intelligence may support a technical or Spellslinger-oriented concept where the current subclass mechanics make it relevant.

Spellslinger makes Intelligence significantly more relevant because that Creed adds arcane spellcasting; most other Gunslingers can usually treat Intelligence as a secondary or concept-driven score.

Strength

Strength is normally a low priority for the standard class.

A firearm build gains little from raising it unless equipment, subclass, or character concept creates a specific need.

Practical priority

Typical Gunslinger:

Dexterity → Constitution → Charisma / Wisdom according to subclass and role → remaining abilities

The chosen Creed can shift the secondary order: Spellslinger raises the value of Intelligence, while social or covert concepts may place more weight on Charisma or Wisdom.