Hysteresis loops and domain structure of as-cast Fe-rich and stress-annealed low magnetostrictive Co-rich bistable wires have been investigated as functions of the distance to the end of wires having different lengths. From the analysis of the changes of the squareness ratio and differential susceptibility at remanence, the existence of conical "closure" domains at the ends to decrease the magnetostatic energy is inferred. The switching process is accompanied by a sudden reconstruction of the domain structure.