Skullmasher continues to elude me

I have been looting the DLC chests on M4 for hours on end. I’ve probably killed 20 or 30 loot skritauris and everything else I can think of has dropped.

Is it just that the RNG gods are unkind and I have not sacrificed enough ammo on the altar? I don’t get it. I’ve hit the scarab and the red chests and nothing…

Are you on xbox?

I got 3 of them if your on pc.