0 - 1mA Meter movement accuracy test

I have a 0-1mA meter in my junk box that I plan to use with a number of test instruments including the following:-

1) DC analog Voltmeter
2) An RF peak voltage detector
3) Various RF power meters

The results show good linearity of the meter. It also shows a difference of 10uA between the measured DC current and the calculated value. One would assume that the error is due to the omission of the meter resistance (ie. assumed = 0 ohms) in the calc value. Calculations show that there is  a 0.22volt drop across the meter.