Except for the heavy machine guns like heir apparent or xenopage, machine guns should be primaries, because as of right now they serve no purpose outside of PvP. Almost all shotguns and sniper rifles do more boss dps than machine guns and why waste your heavy slot for one when currently most primaries, especially ikelos weapons, ad clear faster, at a much better ammo economy. Trace rifles should get the same treatment. They are useless as special weapons, and if they were primaries they would at least be fun to use.