Hi everyone! I recently got an Atrend fiberglass sub box for my C6. I started mounting my shallow mount 10” with course drywall screws and the screws would not penetrate the fiberglass, even when carefully using a drill. I switched to a small drill bit to make a pilot hole and it broke the damn bit! Is this normal? What am I doing wrong? Any help would be appreciated.

I just got it. Turns out my drill bits were garbage. They were even Craftsman, which is surprising. Thanks for the reply!