Gunsmith Rank 2 gives a class specific legendary and rank three gives a class specific exotic. For both rank 2 and rank 3 quests you will have to dismantle rare weapon worth three parts and legendaries worth 5 parts for a total of ten parts to get the gun. Year one weapons do work for this! This will reduce your grind to finish gunsmith quests! tl;dr DONT DISMANTLE YEAR 1 WEAPONS THEY WILL HELP FINISH YOUR GUNSMITH QUESTS