Gallium nitride (GaN) high-electron-mobility transistors (HEMT) are of great interest for pulsed power applications due to their proven capabilities in RF applications. With further advances in GaN power semiconductors, there's an interest in the evaluation of their performance under repetitive overcurrent operation in power electronics applications beyond the manufacturer's prescribed operating parameters. A GaN HEMT from two different vendors were evaluated in a pulsed ring down testbed at 475 V with a peak current above 80 A over a repetition rate of 138 Hz. The testbed employed a temperature chamber to adjust the case temperature of the device during testing. The devices' electrical characteristics, such as transconductance, forward I-V curve and reverse blocking voltage were measured throughout testing and have not shown significant degradation. The collected data from these measurements allowed a comparison of the devices' performance and shows their ability to handle transient overcurrent conditions commonly found in power semiconductor device applications.