High velocity impact behavior of 4340H Steel fragments on thick 7039 Aluminum plate was investigated using ballistic tests, and computer modeling. Fragment simulated projectile (FSP) was fired at various velocities that are within the ordnance range. Measurements were made on the cavity size, depth of penetration (DOP), residual projectile length, and backface bulging. Computational analyses were performed using a three-dimensional nonlinear transient finite element code. A rate-dependent damage plasticity model was used to model the dynamic response of projectile and target materials. Very good correlation was found between computational analysis and ballistic test results in terms of selected parameters. The final shape of the fragments after the impact from the computer analyses matched well with those retrieved from the ballistic tests. This provides good confidence in armor calculations using the material input parameters for this projectile/target system within this range of impact velocities.