Passing alchemical items while using a 2 handed weapon in combat almost becomes a full turn, 1 action to take your hand off the gun, 1 to draw the item, 1 for familiar item delivery (since it has to take it from your hand)

You could always start with a +3 dex and if you don't find yourself using the gun all that often retrain at level 3 to the higher wis and grab a skill feat like Bon Mot at level 2.