Transport and magnetization measurements have been made on 6μ, 720 filament niobium carbonitride yarn. The magnetization data is discussed in terms of the hysteretic loss, the temperature dependence of Jc, the matrix-superconductor bond quality and the doping effects on the high field Jc's. Transport properties are compared to properties obtained from magnetization data. In addition, weak coupling has been investigated in low conversion fibers. The V-I curves show numerous voltage steps, some corresponding to an order of magnitude increase in resistivity.