I know it's been asked before, but I'm unsure on the exact length of the screw.
Does it have to be long enough to drill ALL the way through?
Do you drill your pilot holes ALL the way in?
I bought some drywall screws from ebay for when I order my American Bass XFL 12". I'm not sure if they're long enough, or if they will work.
(If you search "1-5/8" Drywall Screw Phillips Coarse Thread 1lb Box" on ebay you will find them. I cannot post links here, otherwise I would)