I've seen a lot of preds with m4s but the bleeds are weak. The more dmg you do with 10 shots the higher the bleeds are. And since the AK has the highest per bullet damage for the automatic ARs you get the highest bleeds up to 800k-900k per tick. You could switch out Predatory for Deadly if you always got a Healer around for even higher bleeds. You can also use any other AK like Classic or Blackmarket but the Military one has the easiest recoil pattern of them. The MDR is used for Medics, Tanks and Bosses since they dont go down with one bleed cycle of the AK in a 4 man group Legendary.