A delivery wire assembly for delivery of an occlusive device to a location in a patient's vasculature includes a delivery wire conduit having a proximal tubular portion coupled to a distal coil portion, the respective tubular and coil portions defining a conduit lumen. A core wire is disposed in the conduit lumen and having a distal end coupled to an occlusive device, wherein an elongate electrical contact body at least partially seated in the conduit lumen and coupled to a proximal end of the core wire, the electrical contact body and the proximal tubular portion forming a junction. A coil collar is disposed around the electrical contact body near the junction.