All Adverse barrels on the FiNN completely change the gun, lowering its damage per shot but very drastically increasing its rate of fire - to levels unmatched by almost every other gun in Warzone. The time-to-kill is far better with an Adverse barrel than without.
From being able to fire up to 100-rounds before reloading (albeit making that reload process a little longer than you may like), to a variety of scopes (including sniper options and thermals), the FiNN is just as at home as a support weapon as it is helping you storm a building in Warzone or rack-up kill streaks in ...