experiments on the penetration power of various bullets into skin and muscle tissue

The literature cites values between approx. 50 to as critical velocities for spherical or ogival projectiles. This test was designed to determine the general validity of these values. “Critical velocity” is defined as that velocity, below which no penetration of the skin occurs. A series of 212 test shots was fired after the powder storage chambers of caliber 9 mm and caliber .45 cartridge cases were altered. With the appropriate charges, velocities varying between 50 and 100 m per sec were achieved. The shots were fired orthogonally into the muscle tissue of the upper thigh of corpses and into a combination of human skin + Mipoplast®. The skin was tightened in a wooden frame and a block of Mipoplast® was directly attached. (Preliminary tests showed that projectiles nearly had the same penetration power in Mipoplast® as in muscle tissue.) The projectile velocities were determined by a „shoot-velociter Re-Tronik“ with a resolving power of 10−6 sec. Projectiles were considered as having penetrated the skin, when they entered the epidermis for a distance equal to the caliber diameter. In order to determine a ballistic coefficient and a conversion factor, the depth of penetration into muscle tissue of the upper thigh or into Mipoplast® respectively was measured. The following bullets were used in the tests: 9 mm :lead ball 5.3 g lead, round nose projectile with a short cylindrical portion, 6.2 g lead, round nose projectile with a long cylindrical portion, 10.6 g conical, flat nose projectile 7.9 g conical, pointed nose projectile 7.9 g caliber. 45 : lead ball 9 g lead, round nose with a cylindrical portion, 14.7 g and finally a 4 nun lead ball. 47 g. The projectiles were fired from a Walther pistol P 38, caliber 9 mm Parabellum, a colt pistol, Government 1911 A1, caliber .45 ACP and from a revolver Rohm RG caliber 4 mm Rdz. The tests results permit three functional evaluations per series: (1) optimum parabola of second order, (2) optimum line (linear regression), (3) logarithmic function (log. nat.) The following results were obtained: The penetration power of a projectile does not depend primarily on its velocity, shape or cross-sectional load, but is determined by its mass. The following conclusions could be drawn, concerning lead projectiles fired by us: The greater the mass of a projectile, the lower the „critical velocity“ (vcr = 162.1 • e−629 m) The conversion factor for the penetration power of the examined projectiles comparing skin/Mipoplast® and skin/muscle tissue was determined to be 1.2, i. e. the depth of penetration into skin and muscle tissue is 1.2 times greater than into skin + Mipoplast ®. An evaluation of these results shows a “loop-hole” in the Gun Control Act, since the legal requirements for the unrestricted acquisition of firearms only considers the kinetic energy of the projectile (less than 7.5 J). However, all lead ball ammunition with diameters of less than 6.2 mm definitely does penetrate the skin at that energy level. Another conclusion is that projectiles fired from unlicensed weapons such as BB guns operated by air pressure, spring or CO2-cartridge (caliber approx. 4.5 mm) can achieve penetration with as little energy as 4 J. Even if one wants to maintain the present differentiation between exempted weapons and weapons covered by the Gun Control Act, based on the energy level of 7.5 J, the legislature would have to establish a minimum mass for the projectiles. Considering the results obtained, the present limitation of the kinetic energy of the projectiles of 7.5 J alone does not guarantee the level of harmlessness the present law supposes. A projectile mass of less than 1.4 g and a kinetic energy of 7.5 J can reach a level of danger that up now has not been recognized by the legislature. Those findings ought to be considered when licensing weapons according to Para 21 and 25 WaffG (Gun Control Act of the Federal Republic of Germany) as well when prohibiting weapons according to Para 37 WaffG and Para 8, Section 1, Number 1, of the first WaffV (Weapon Regulations).