The angular momentum exchange between a binary magnetic neutron star and its accretion disc is considered. In a previous paper it was shown that if the disc's magnetic diffusivity,η, is due to buoyancy or turbulence, disruption occurs where the magnetic extraction of angular momentum starts to dominate that due to viscous advection. The disruption radius is significantly larger than one half the spherical Alfvén radius, often previously used for the disc's inner edge.