An optical lever system was used to observe the impact shock wave arrival and free‐surface motion at the rear surface of a 2.54‐cm‐thick 2024‐T4 aluminum target plate. The projectile was a 0.636‐cm‐diam. steel ball and struck the target at a velocity of 5.28±0.11 mm/&mgr;sec. The shock‐wave data, in the range 30–1 kbar, extend data by Fowles to lower pressures. The measured elastic shock velocity of 6.23±3% agrees with ultrasonic values and with elastic shock values by other investigators.Elastic shock amplitudes do not maintain a constant value as in one‐dimensional experiments, but decay at a rate faster than predicted for spherical elastic waves.