When appling a specified torque to a nut/bolt combination always apply torque to the nut while holding the bolt stationary. Tightening or torqueing the bolt applies a twisting force to the bolt shank which would give a false torque reading. This method would apply to screws as well if they are installed in combination with a nut. Hold the screw/bolt, and tighten the nut. In actuality you are really s t r e t c h i n g the shank of the bolt or screw and if the shank has a twisting load and a tension load at the same time,.............well thats not good. False torque readings will also be indicated if using a socket extension, longer extension=larger error, due to the extension twisting when applying torque to the nut. Also, never apply thread lub as this will give a false or inaccurate torque reading.