If "effective" means changing her decision, not likely. IMNSHO OccupySomething, BLM and FSA have raised the protest bar to the point civil disobedience is required to get any attention. Civilized protests are passe at this point. We should try, but I have limited expectations.
Protesting to Gov. Baker is useless. He has no authority over the AG and has said he agrees with her.
Getting the legislature to respond depends upon getting them to see her actions as a threatening over-reach into their space, regardless of the content of her actions. The danger is the legislature amends the law to codify her "reinterpretation".
Long-term, getting recall enabled for state officials might be more effective. One would have to make common cause with non-gun groups with a similar goal.