Destroy 30 Revenants’ weapon arms
Resident Evil Revelations 2 – DISARMED Achievement / Trophy Guide
Near the end of Barry’s story you come to a gate that is locked with chains. This area has a couple of Revenants, but only 2 have a weapon for an arm which is what you are looking for.
Run up to the gate and interact with it. A Revenant will then break through the fence behind you. Try only shooting it in the arm or chest to destroy the weapon that is attached. Don’t kill it early by shooting the red bubble before getting the weapon off.
After you’re done with the first, run to the house next to the crane and find the second one that is hiding in one of the back rooms. You can now reload the checkpoint and repeat this. Your ammo will be filled up again.