Is it the item being hard to find or the enemy that drops it being mean?

I ask because while every Mil Lilly ive seen has dropped a rare (either a sense plate, aura field, sange and agito 75) every rare rappy ive seen has not dropped a rare.

While I had an oran I had 4 Tollaw drops over 400 hours (general play not solid searching) netting me Twin Chakrams....can I expect to see 4 Handgun:Millas over the same period with my Whittel or will I be lucky to get 1?