Not always, in my experience oracles go down depending on the amount of lag, i almost always use VOC, never run out of ammo and even use it on Atheon occasionally. If everything is going well, no lag, i take oracles out with fewer than five shots with VOC. I also use fatebringer and if things aren't so great, lag, i turn to corrective measure. I got the clears to back that up.

OP is talking about Hard Mode...