I've searched the forum, but there are too many topics on this archetpype and in none of them I found a precise answer.
So, correct me if I am wrong.
Just reading the archetype: aim the target, enhance the weapon (swift), chant the spell (standard), pull the trigger. The bullet flies and hits touch AC of the target in a range of 20 ft: 1dX damage plus spell effect (ST as usual).
Why this interpretation?
Most of all, because it says "in a spellslinger's hands, they [his firearms] *both* fire projectiles (bullets and pellets) *and* cast magic". But also because it has no sense to me give up 4 schools of magic, shot within 20 ft and risk misfire (for something a simple ray can do in a much more worthwhile and safer manner) if the firearm does not shot anything XD
I listen to your wisdom :)