/equip ammo "Silver Arrows"
/ws "Barrage" <t>
/equip ammo "Iron Arrows"
Yes, I think you mixed up Barrage from the other WSs like Piercing Arrow.
If you DO end up putting equip statements in your macro, there's no need to make the last line to swap your arrow back...it's redundant.
If you precede each of your macros with the first line being the "equip ammo" statement that should take care of it.
Also, make sure your arrows are typed out in *singular form". (e.g., Silver Arrow, Horn Arrow, etc.)