Ever since RoI dropped, I've been seeing a lot of claims that Firefly on kinetic primaries deals solar damage. As a Firefly enthusiast since year one, and believing this to be patently false, I intended to call bullshit on the whole thing once and for all. So I set about testing, and what I found shocked me.
Out of 13 kinetic primaries tested, 6 dealt solar damage.
These are my results:
|Hung Jury SR4||yes|
|Free Will III||yes|
|Not Like the Others||no|
|Treads Upon Stars||no|
|Ace of Spades||no|
|Y1 Gheleon's Demise||no|
I found this very strange, so I did a couple other tests:
I tried the Vanity and the Treads against arc and void shields, and they still did kinetic damage.
The Free Will I used also had explosive rounds, so I tried that against a solar shield. Even though the Free Will Firefly dealt solar damage, the Explosive Rounds still dealt kinetic.
My conclusion, for what it's worth:
It's a bug.
In year one when Fatebringer was king, it was common knowledge that the explosions it caused, whether by FF or ER, dealt arc damage. Back then you couldn't roll FF on any other hand cannon, but you could get it on regular legendary scout rifles, and in that case it dealt kinetic damage. To my knowledge it had always remained this way – that is to say, a weapon always dealt the same type of damage, regardless of its perks. This is easily demonstrated in year three with sniper rifles, because most can roll both FF and ER.
Because less than half the weapons I tested actually dealt solar, coupled with the fact that ER on the Free Will dealt kinetic, I can't believe it was ever intended that they do so. The patch notes from 2.4.0 through 184.108.40.206 only make one mention of Firefly, and that's just a "possible fix" for the bug that used to crash your console. Maybe when they fixed that we got some unintended solar damage?
Thanks for reading – hope some of you find this useful.