Hi @JohntheRipper,
Thank you for your question about anchoring your bookcase to the metal studs in your home.
If you are screwing directly to a steel stud, then there will be no need for an anchor; just screw through the anchoring bracket straight into the stud. The anchors they supply are for use when you are anchoring to a masonry wall.
I'd suggest using 30mm Gold Passivated Bugle Head Plasterboard Screws. They are typically used for fixing plasterboard to both timber and metal studs. I have used these exact screws many times for anchoring things to steel studs.
A pilot hole is not really necessary. If you apply pressure, the screw will eventually break through the steel, the thread will engage, and it will pull through.
In saying this, if you have trouble, a small pilot hole with a 3mm HSS Drill Bit will help the tip of the screw get through so that the thread can engage and pull the shaft of the screw through.
The stud finder and drill you have linked to would be more than capable of this job.
Let me know if you have any questions or concerns. I am more than happy to assist further if required.
Jacob
