I have an easier solution for you. Like many, I bleed heavy ammo because I use the carry extra heavy ammo perk on my gear. Don't have much choice but to use it, because it is my raid gear. I equip my icebreaker as my special, and typically a hand cannon or another primary that I can empty out quickly. I quickly empty out all of my primary and heavy ammo so I'm only left with my six icebreaker rounds. I then switch to my icebreaker and begin to kill as many ads as possible. Every kill will drop a heavy ammo pack on the ground until the primary ammo regenerates itself, While I don't typically like to have to do that, in my eyes it's only fair considering how much ammo I have lost over time.