Review on Hillman 47748 Galvanized Square 8 Inch by Mike Johnston

Screw heads break off. Plywood 11/32 over standard 2x3. Building a wooden ramp/jump for bikes. Once the screw head reaches the plywood and I keep moving to get the screw head below the surface, the screw head breaks. Didn't have this problem with 2" stainless steel screws from the same company. Maybe I need a different screw head that allows for a slight countersink. Or do I need to drill a shallow hole first.