This talent says it can be activated as a Free Action. However, should there not be a rule/house rule that it must be done BEFORE any shot is taken? Granted, it is once per combat encounter.

~ alemander

We've always understood it as such since it's not an evasive free action or anything, and the description lends itself to being done before you shoot or use the weapon in question.

not really a need to have such a rule. you can activate it whenever you want. since it last for your round it would be a waste to fire first and then activate it. moreover you cant break your actions so you cant roll to hit and then decide to use it before you roll for damage. free actions are free but do not interuppt other actions. hope this helps