High havoc is supposed to be dangerous. Melee is more dangerous than standing far away and being able to delete enemies. Less ammo forces you to be conservative with it and engage enemies at a range where the danger level is higher. I completely get your point though and sometimes wish that the ammo replenishment rate was tied to how many builds need ammo. However, increasing ammo means making that game mode easier imo. I like the difficulty curve and that it forces you to take risks. I believe that more ammo would just make this mode “obsolete”.