Barrage of Pain not working with Boundless Blows

[TormDM]

Hey guys, is this intendet, that the passive talent of marksmen "barrage of pain" does not stack the "bow mastery" buff if you are channeling flurry with "boundless blows"?

It feels kinda weird to stop and go flurry to stack bow mastery, esp. with "accelerating impact" when you get bonus damage the longer you channeling.