Microprobe analysis, neutron diffraction experiments and 5 7 Fe Mossbauer measurements have been performed on powder samples of the ternary HfFe 6 Ge 6 -type RFe 6 Sn 6 intermetallics (R=Sc,Tm,Lu) and on the new ZrFe 6 Sn 6 compound. Both microprobe analysis and neutron diffraction indicate an under-stoichiometry in R elements (~10%). According to neutron diffraction study, the magnetic structures always consist of ferromagnetic easy-axis (001) Fe planes antiferromagnetically stacked along the c-axis (+-+-) with μ F e close to 2.3μ B at 2K. The 5 7 Fe Mossbauer spectroscopy reveals that a fraction γ of iron atoms, roughly proportional to the above mentioned under-stoichiometry, have moments which deviate from the c-axis. These observations are discussed in relation to the easy-plane magnetic arrangement adopted by the FeSn parent compound.