If you have a random MW chest piece with scavenger mods added and swap to it before rallying you get extra heavy rounds. You can then swap back again to normal chest bit straight away and won't lose the extra. Can bump your dragons breath ammo upto 12 round with this. Works on other heavy weapons and specials. Can be a big help especially in tanky boss fights and git heavy encounters.
Did you take down the vod for the campaign stream? Clicked on the first mission video and you said you werent including cut scenes so I'd rather watch the stream but I can't find it