on what hm do that drop on(if it does)? all i've found is that it drops on karragas palace story mode.

Up until 1.2, the only way to get it was through operations (KP, like you mentioned). It is now also a drop from the last boss of Lost Island HM, along with the rakata chest as well as various other columi from the earlier bosses. If you're a sentinel, marauder, gunslinger or mercenary, it is also possible to rip out the mods from the columi offhand and put them in a main hand custom weapon, effectively making it columi in all intents and purposes.

HM EV; Soa specifically.