Actually, the special economy doesn't need to change first to allow to re-introduce the guns. At least from my perspective as a longtime player. NLB is a was a primary weapon. Just make it a special weapon and improve the perk. It doesn't need to stay a primary weapon. Icebreaker and Invective did regen ammunition over time while staying alive. Just change their ammo regeneration to only work as a chance when making primary weapon kills. Problem solved. In PvE you get enough special weapon drops. In PvE you have enough trash enemies that can recharge your Icebreaker/Invective then. In PvP Special Ammo drops like candy. In PvP you do a lot of killing with primaries.
Primary kills drop special ammo and primary weapons disorient the ease of use of special weapons. Assists should not drop ammo for special weapons.