Billy Blasted reload inconsistent with tooltip

[rundo]

After leveling the Blasted skill, when Billy performs a heavy melee on a hero or neutral creep he fully reloads, but does not reload at all when performing a heavy melee on a trooper. The tooltip says that non-hero melee hits should be 35% effective, meaning a heavy melee on a neutral should give 35% max ammo and a heavy melee on a trooper should also give 35% max ammo.