The Head Injury Criterion (HIC) is an injury metric that gauges the risk of head damage following a dynamic impact. The HIC must be evaluated following Federal Aviation Administration (FAA) and National Highway Traffic Safety Administration (NHTSA) standards on occupant head impact safety. The HIC is generally determined by conducting several full-scale sled tests with appropriate regulations. To overcome the drawbacks of FFST, researchers have developed component-level testers, one such device is the Head Component Testing Device (HCTD). Attempts have been made to save testing costs and increase occupant safety by using computer modeling analytical techniques for validation. Through validated computational modeling techniques, one can explore the effects of higher head velocities, and different properties of bulkhead on HCTD systems by saving the destruction of apparatus, cost, and time. The goal of the present research is to compare the Hybrid-II and FAA Hybrid-III ATD isolated head-neck responses, using a Head Component Testing Device by employing several stiff and soft bulkhead head impacts. Computational models of HCTD are developed with Hybrid-II and Hybrid-III head-neck systems in MADYMO. The constructed models are validated against experimental tests from previous research. The computational bulkhead impact simulations on the ATD head are performed by controlling different SRP-to-bulkhead distances, head impact velocities, bulkhead properties, and modes of operation. Head paths are plotted, and computed HIC values are used to compare Hybrid-II and Hybrid-III head-neck responses. The results of this study explore the effects of test variables on resulting HIC values in comparing the Hybrid II and Hybrid III head-neck responses.