flare guns afterburn is additive 

Follow-up video from the scorch shot bounce one.
Flareguns apply 15 dings of afterburn
If you shoot someone on the 14th ding then 16 dings will play
Note that the first try on detonator landed right after the afterburn worn off which is why I shook the mouse and sped through it. Too lazy to do cuts for these small vids.

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