E-Step calibration

[Rockel83]

I'm trying to calibrate my new A20M.

And I think one of the most important steps to start with is to calibrate the E-steps.

I've noticed that there's a lot of diffrences about this value in several sourcecodes for this specific printer. Varriating from 395 to 430.

When I just measured and calculated this vallue myself by measuring 120mm at the entrance of the extruder and feed 100mm through the heated nozzle, it gives me values around 430.

But when I disconnect the bowden tube and feed 100mm cold straight through it, than it give me values around 400.

This is a big diffrence.

Does this mean my extruder is slipping when feeding through the hotend?