12.9 sounds like he's gone hi tensile
dunno about your side of the globe but even the cheapest black steel screws
from china etc are still pretty decent quality, none so bad they're useless
much more common for RC'ers to have hopeless wornout tips on their drivers
That is the truth with any type of screw and driver combination!!
You have to have qualitity on both ends or else it doesn't work. Maybe the screws will do the trick as I'm curious about the screws, the patch locking and how well they will work in the field overall.