Back-diffusion of electrons to cathode is studied by Monte Carlosimulation for realistic argon cross sections. In particular westudy the influence of different aspects of back-diffusionmodeling with an aim to simplify the models used in modeling ofplasma displays, low pressure gas breakdown and detectors of highenergy particles. It was found that the initial electron energydistribution is one of the critical parameters and affects thecalculated escape factors very much. The same is true forreflection while angular distribution of initial electrons has avery small influence on the escape factors. The model of crosssections combined with the selection of realistic initialconditions was shown to represent the back-diffusion in argon verywell giving good agreement with the available experimental data.Most importantly it was found that the range of electronsreturning to the cathode exceeds by far a mean free path and thatthe number of collisions that they make before returning is quitelarge. Thus it was found that for a relatively high pressure ofaround 10 torr the range exceeds d= 1 cm (at E/N=12Td,1 Td= $10^{-21} {\rm V}{\rm m}^{2})$ and therefore application of the escaperatios below that value of p d (where p is the pressure) isquestionable, i.e. under those conditions calculations should beperformed for the actual geometry.