Two improved kMC models for investigations of the magnetic properties of finite-size atomic chains are presented. These models take the possible noncollinearity of magnetic moments into account. The spontaneous remagnetization of ferromagnetic Co chains on Pt(997) surface and antiferromagnetic Fe chains on Cu2N/Cu(001) surface is investigated in the framework of our models. The results are compared with the results of the simple kMC model. It is also shown that a single domain-wall approximation can be successfully used to estimation of the reversal time of the magnetization. Therefore, the improved kMC models can be used for analytical calculations as well as for computer simulations.