We have investigated the effects of 24.3at% Dy substitution on the La site in the ferromagnetic perovskite La_0.7Ca_0.3MnO₃. Results show a randomly canted ferromagnetic state below 65K with a reduced metal–insulator transition. There is no breakdown of ferromagnetic domain structure at T˂65K (covering the temperature range below 35K where resistivity shows an upturn, indicating a reentrant transition to an insulating behaviour). Reduced geometrical tolerance factor and increased variance of the La-site ionic radius are responsible for the observed changes.