Hunter · Marksmanship · tier 5 · from level 30
Barrage
+64.4 Volley
3/3 · level 60 · per cast · and 2 more
Barrage
Rank 3/3
Increases the damage done by your Multi-Shot, Aimed Shot, and Volley abilities by 10%.
Averages, counting crits and misses, for a level 60 Hunter with a typical weapon and no other gear or buffs, against a target your level. Worked out from the game's own data, the same way as the Foresight addon.