A series of tests were conducted to determine the velocities necessary for lead air gun pellets (calibers .177 and .22) and caliber .38 lead bullets to perforate skin. Human lower extremities were used. Caliber .177 air gun pellets weighing 8.25 grains required a minimum velocity of 101 m/s (331 ft/s) to perforate skin. The energy per area of presentation ratio E/a was 1:86 m X kg/cm2. Caliber .22 air gun pellets weighing 16.5 grains needed a minimum velocity of 75 m/s (245 ft/s). The E/a was 1:3 m X kg/cm2. A round nose, caliber .38 lead bullet weighing 113 grains perforated skin at 58 m/s (191 ft/s). The E/a was 1.95 m X kg/cm2. These studies appear to indicate that lightweight projectiles need greater velocity to perforate skin than do larger caliber, heavier bullets.