Today I looted pixie harness (M) on corns after only roughly 50 or so kills.
I hunted cornundacauda however and after 600 confirmed kills only one horn.
No L items, no armor parts, mainly oil, shrap, ammo, and a little hide.
I am hoping an armor part drops within the next two hundred kills, however as I just looted
and uncommon drop ( horn ), that probably took place of an armor piece I could have received.
I estimate true uncommons usually loot every 300 - 400 kills, you may miss and catch both pieces
after 700 - 800 kills. Some uncommons though like UL weapons post vu15 are more very uncommon,
but not quiet rare as they require 3000 - 4000 kills and you may miss in your first 3-4k kills and pick
up one or two in the second round.
True rares seem to be roughly 30,000 - 40,000 kills, while extremely rare is 300k - 400k kills still with
a big chance at a miss in your first round. Unless you are lucky enough to hit very early in your kill round.
This adds up to a lot of man hours and peds cycled very quickly, which is why I am only seeking uncommon items for my UL thread atm.