When Kruber Huntsman is using the repeater gun and spins it to fire 8 shots at once, if he pops his ULT prior to the magazine being empty he gains 5-8 extra shots before needing to reload, depending upon how good you are at timing the ULT as close as possible to the end of the magazine.
To recreate have Kruber Huntsman spin the barrels and start firing, as close as possible before he needs to reload pop the ULT and he’ll keep on firing another 8 rounds, giving a possible 16 shots without needing to reload.
This is present before 2.0, so it’s not new. I’ve been using this to quickly burst down SV patrols. It gets sillier if you have a Concentration Potion in hand.
As for the topic whether it’s a bug or not, I have to say it’s not a bug. Enjoy using it!
This isn’t anywhere near the levels of stupidity of previous possibilities with huntsman like the fabled Sigmar’s minigun. Looks fine to me. Huntsman is a crappy character now anyway.