So i just got the legendary minigun, Ashmaker. It apparently does 15 extra points of fire damage.

That's vague as hell, i don't like it

Does that mean each bullet (which normally does 8 damage) now does an additional 15 damage? That sounds horrendously OP

Or does it mean that bullets just apply/refresh a non-stacking effect that does 15 damage (over what time period?) in which case, that's pretty svcky.

I need more explanation here, how do firedamage attributes/mods work?

From what I understand fire, bleeding and poison damage linger. Each bullet sets targets on fire dealing x amount of damage over time, not all at once.

Also this applies somewhat differently to shotguns. Each shot from a shell procs the status. I have one that cause bleed damage. Thing is just nasty because if all shots connect their health just dips. Took down a legendary Deathclaw matriarch in seconds.

Its damage over time, but you only need to hit them once to set them on fire. Ashmaker isnt that good to be honest.

This post is confusing and contradictory, i think

Does setting a target on fire have any extra effect if they're already burning?

The fire damage adds a cumulative dot to the target. Essentially fire enough bullets, switch targets and the burn damage will do the rest. Dots in general are only useful against targets that have lots of health, imo.

I'm not sure if this applies to burning as well, but with bleeding anyway each bullet procs bleed for he same amount

Ok i'm testing with the ashmaker, it svcks.

Enemies burn for about 3 seconds when hit, and the duration of this varies depending on how long you fire, and the damage is miniscule.

Not only does it NOT stack per bullet, it doesn't even refresh the duration. Enemies burn for 3 seconds after the first hit, not after the last one. You have to keep firing for longer than 3 seconds to make them burn more than that.

Ashmaker is [censored], and fire damage svcks