undone surge
The Hemo Magazine item description shows 0.2 points of damage per shot, but player takes 1.0 damage per shot. With the Pulse Rifle and Homing Rounds, delayed impacts seem to be proc'ing the HP hit. I am routinely losing 1 HP per tick while under the 50% health margin due to bullets out chasing enemies off-screen.
waxen dust
I think it only shows the damage when you lose whole numbers of hp. It seems the proc effect is decided at the time you shoot [the text says 'shooting while above 50% health'], not at the time it hits. I've killed myself a handful of times with hellspitter, piercing, and homing. Possibly working as intended, but not intuitive.