The simplest option is to take a slightly larger drill and countersink the screw a bit into the stud. Exactly how much is needed you'll have to determine through trial and error, but stud+plasterboard is almost 60 mm, and the thread doesn't sit flush on the back either, so there's an additional few millimeters there, totaling maybe 65 mm? If you have a 50 mm screw, you need to countersink at least 15 mm.
The second option is to buy a longer screw, which can be found at real building supply stores. Essve sells M4x80 and M5x100. If that's not enough or they can't be obtained, you can cut a piece of threaded rod from Biltema and attach a nut.
Now I'm giving up. I can't even put up a damn rule without totally failing. I've bought different mollys, even some kind of wood screw molly variant that wasn't supposed to fail with (according to the guy at the store), I've tried EVERYTHING. The damn rule won't attach. It doesn't work. How damn useless can you be? How sealed too. It won't attach!
Yes, it widened. But the regel still refused to fit
Ok. If you screw in the screw so it just catches the threads without the regel, how far out does it stick from the wall and is it secure enough that you can't pull it out at all?
. Nothing wrong with the Molly. But the rule refuses to attach.