Investigations on a small single crystal of GdCuSn revealed, contrary to earlier studies, that compounds of the type RCuSn crystallize in the GaGeLi-type of structure (space group P6₃mc). In the case of NdCuSn, down to liquid helium temperature, no indication for long range magnetic order exists. For the remaining two compounds antiferromagnetic order was found below 25 K. ¹¹⁹Sn Mössbauer spectra were recorded between ambient and liquid helium temperarure. Below the magnetic ordering temperature the Sm and Gd samples showed reasonably well resolved spectra, in contrast to Nd. In the case of NdCuSn and GdCuSn a sufficient correlation between μ_eff and B_eff was obtained.