The 3% physical damage reflect misson modifier seems to be acting oddly.  Sometimes I'll do myself no damage at all.  

On my gravgun sometimes I'll do myself some damage but it is manageable if I'm careful - this is fine.  On my power hammer I can sometimes one-shot myself on a single target attack which seems somewhat off, since it is only one target, I have damage reduction and physical resist in play.  Am I really occasionally doing an attack of 200k+ damage?

If I was hitting a big group with AoE and one-shotting myself I could understand (though curiously this seems to do me less damage), but this is only happening on a single target attack, and only then on a melee weapon so far.