The keys to any screw driving application are quality control of the manufacturer - paying attention to matching the shape and tolerances specified by the OEM or other standards setting bodies. Many fasteners and bit drivers today aren't paying enough attention to the details. I learned this long ago from my father who was a professional mechanic and part-time gunsmith. Quality guns have lots of unique (slot head) screws - cut so their slots line up when driven perfectly home! Bung one up, and you dramatically reduce the value of the gun to a knowledgeable buyer. To remove them without bunging them up, you need to have a closely fitted driver bit, and my dad had a wide ranging set which he got from Brownells (don't know if they are still in business). From personal bad experences, I have learned to stay clear of off-brand screws, including certain decking screws that have Phillips heads or combo-head (Phillips and square drive). I prefer genuine Phillips brand screws and drivers, or square drive screws from McFeeley's for decking, and more recently find myself gravitating towards PZ (Euro) screw head fastners, especially genuine Spax brand for general purpose woodworking. Genuine Phillips decking screws used in conjunction with a genuine Phillips brand driver grip tightly on the driver, even when pointed ~30 down from horizontal, and do not cam out easily. They work about as good as McFeeley's square drive screws in my experiences. I have several different P2 tip inserts from different manufacturers and they are definitely not all equal!
A quality Pozidrive bit is the only way to go with Euro screws, if you want a quality job and don't want to risk bunging up the screw heads. They grip the screw heads very well, as others have said.
Dave R.
