Understanding the epoxy polymer’s dynamic behavior and its relationship with strain rate and specimen geometry is crucial for analyzing and designing polymer matrix composites (PMCs) under dynamic loads. The current study involved conducting high strain rate studies on EPOFINE®-1564, a liquid epoxy resin made of Bisphenol-A-Diglycidyl ether (DGEBA), using the Split Hopkinson Pressure Bar (SHPB). The pulse-shaper method is utilized to generate an incident pulse with a longer rise time compared to the duration needed for the specimen to attain stress equilibrium. This study aims to examine the influence of three pulse shapers—cotton gauze bandage, copper, and epoxy—on dynamic stress equilibrium, and constant strain rate. Additionally, the behavior of epoxy polymer is investigated at dynamic strain rates for varying aspect ratios (l/d) of 0.4, 0.5, and 0.75. The findings indicated that the specimens’ stress versus strain behavior and their corresponding magnitudes of strain seen in the strain pulses were significantly influenced by the strain rate and aspect ratio (l/d). Peak stress values rose in response to higher l/d ratios and strain rates.