I have one of the Apple set ups you mentioned and my scale will read about 4 or 5 lbs light when using it that way. So regardless of if it is correctly calibrated it still shows a difference between the " standard" way of checking draw wt and using the Apple machine with the scale hanging. I believe Len is correct in that this would be due to the weight of the scale would have to be added to the reading or the scale calibrated with the set screw to compensate .