Greed

root@jakobs-db:~$ cat description.txt

A unique Jakobs pistol notable for two unusual traits: it is always incendiary, and aiming down sights does not slow your movement at all. That gives it a more mobile feel than most Jakobs revolvers, even if its overall performance is fairly average outside flesh-heavy matchups.

root@hyperion-db:~$ cat notes.txt

Its full-speed ADS behavior comes from having no scope part at all rather than the usual sightless setup. Only Greed and the Interfacer can spawn this way. With enough Expertise and skill-boosting class mods, a Commando can move extremely fast while aiming. It can also be farmed repeatedly by re-entering The Leviathan's Lair and using co-op respawn tricks to spawn inside the Leviathan before killing Roscoe.