As an alternative to a Cha-based Gundolon is to go Pistolero (or straight Gunslinger) and take 5 levels to gain Dex to damage.
The advantages are reduced misfire, and your bonus damage is always on (don't need to spend a Swift-action+Grit).
The disadvantages are you'll need to wait til Gunslinger 5 for the bonus damage, and you will have to boost Wis to have a decent Grit pool, while still retaining some Cha to cast Summoner spells (depending on your planned Summoner level, you only need 13-to-15 Cha).

NOTE: I am aware that you can take multiple archetypes, so long as they don't replace the same feature. As posted on the pfsrd (I don't have the book), there appears to be no conflict between Mysterious Stranger and Pistolero. But Pistolero's 'Pistol Training' is obviously meant to replace 'Gun Training'. Mysterious Stranger has already traded away Gun Training, hence, you cannot take both.
Insert Sad-Face as you can't get Dex AND Cha to damage.