A computational study of tungsten wire array z pinches on the Z facility at Sandia National Laboratories shows that individual wires form a core–corona structure early in the current pulse. Further analysis indicates that at 1 mm or smaller interwire gap, the expanding and later merging wire plasmas prevent the growth of m = 0 sausage modes. Although a completely uniform shell is not observed in the simulations, the Hussey–Roderick profile—a characteristic of uniform shell implosions—is seen. Differences in shell characteristics between small- and large-diameter wires are observed, possibly explaining performance differences between these two arrangements.