This is a combination of screw length, washer thickness and recess, and insert depth. I remember that Gnu or Roxy (maybe both) sent around new hardware kits after having shipped their 2012 bindings last year. Do you know if the hardware on yours had been swapped out? Likely worth an email to the seller or to Gnu. Post up a pic of the hardware you were sent with a reference (measuring tape, ruler, etc) and we will be happy to compare to the correct kit and if we can assist we will get you straightened away.