The main focus of this work is to discuss the influence of the projectile’s length on the results of a Split Hopkinson Tension Bar (SHTB) experiment. By using the commercial software ABAQUS, finite element simulations of high-strain-rate tension experiments are accomplished on Aluminium 7017-T73 alloy specimens when varying the length of the projectile employed. The finite element analyses described herein are applied to simulate the effects of the variation of the projectile’s length on the measurements obtained in the incident, reflected, and transmission bars. Different strain rates are obtained when varying the projectile’s length always provided that its speed remains constant. The simulation results show that the projectile’s length has a significant effect on the strain obtained in the specimen and also on the subsequent stress-strain curve of the specimen. In view of this research, it can be concluded that the projectile’s length is a factor that can resolutely influence the interrupted dynamic tension experiment results since it has a significant effect on the strain obtained within the specimen. The simulations also provide complementary information to the experiments and an in-depth understanding of the specimen’s behaviour.