Mage Bullets (Su): A spellslinger is adept at transferring spell energy into his arcane gun attacks. As a swift action, he can sacrifice a spell and transform that energy into a weapon bonus equal to the level of the spell sacrificed on a single barrel of his firearm. With that weapon bonus the spellslinger can apply any of the following to his arcane bond: enhancement bonuses (up to +5) and dancing, defending, distance, flaming, flaming burst, frost, ghost touch, icy burst, merciful, seeking, shock, shocking burst, spell storing, thundering, vicious, and wounding. [...]
Why can i found between the special ability "Spell Storing"?? In fact Spell Storing is an ability of melee weapons, while SpellSlinger use ranged weapons.
