oil barrage plus projectiles

Hey guys,
I have a question about oil barrage and i mean the non-power charge version. Maybe someone knows better than me.

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Once Ignited, Oil Ground adds 100% of this Attack's Fire Damage as unscalable Damage to the Ignite

So oil barrage has 3 projectiles. let's say i add 3 to it and have 6. Does this mean i get double the unscalable damage to the ignite? Or do the projectiles only count for the initial hit damage?

Also does it matter if i ignite it myself or let a minion do it?

Thanks in advance!

https://poe2db.tw/us/Oil_Barrage