You can get some screws that are made for this job, they have a large head with a screwdriver slot in then a thin shaft that slides in the luff grove then a wider thread with a nut on it in the shape of a a small plate which has teeth type corners that bight into the rear of the luff groove.
Try a Selden Agent or someone like P@B .
If ever you use self tappers in a mast, get the type that has a blunt end not a point. These points rip into your halyards!
CP