CIB's shooting experiment

The CIB released the results of its shooting experiment in late June; see page A3 of China Times, June 25, 2004. They used pig skin over a life-sized dummy, covered with clothing. From the photograph released by the CIB, reproduced as photograph #78 in [L1], it is clear that the shirt used by CIB was different from the shirt Chen wore on March 19. They used pistols with barrels replaced by smooth bore tubes, and fired modified bullets with different amounts of propellant. Ten paper boards were placed along the trajectory, one meter apart, to demonstrate the yawing and tumbling of the bullet fired from the smooth bore pistol. The CIB's test results and conclusions on the lead bullet, based on 3 valid shots, released to the public through the press on June 25, are as follows.

(a)

A modified bullet, fired from a modified smooth-bore pistol, yaws and tumbles immediately after leaving the muzzle. In comparison, a bullet fired from a rifled pistol is stable for the first ten meters.

(b)

The three valid shots, with 90% propellant, all penetrated the jacket, the shirt and the undershirt, grazed or penetrated the target pig skin, but none penetrated the undershirt or the shirt on exit.

(c)

The energy density per unit area of the bullets is $123\ {\rm J}/{\rm cm}^2$, far exceeding CIB's ``practical wounding criterion'' of $20\ {\rm J}/{\rm cm}^2$. Thereafter the CIB ``assessed and determined'' that the lead bullet in the March 19 shooting ``had enough energy to penetrate clothing and cause graze wound'', and that the trajectory and the wound ``was consistent with the actual situation.''⁶⁷

In the official CIB report [CIB2] of their shooting experiment, more specific description of the three valid shots:

• Bullet #3BG12 penetrated the jacket, the shirt and the undershirt, and stopped between the undershirt and the pig skin. The bullet also grazed the pig skin. The length of the graze mark was approximately 3.6 cm long. The bullet had a velocity⁶⁸ of 177.8 m/sec; it did not re-penetrate the undershirt.

• Bullet #3BG12-1 penetrated the jacket, the shirt and the undershirt, then entered the pig skin. It moved into the fat layer and stopped in the fat layer. The distance from where the bullet entered to where it stopped was approximately 11 cm. The bullet had a velocity of 180.3 m/sec; it did not re-penetrate the undershirt.

• Bullet #3BG3-12-1 penetrated the jacket, the shirt and the undershirt, and stopped between the undershirt. It grazed the pig skin, and there were two separate graze marks. There was a graze mark on the inner side of the undershirt, approximately 6 cm long. The bullet had a velocity of 181.7 m/sec; it did not re-penetrate the undershirt.

The official CIB report [CIB2] concluded that,

``A home-made bullet, fired from a modified toy gun, can penetrate the jacket, the shirt and the undershirt, graze the pig skin, and does not penetrate the jacket on exit. It is possible for such a bullet to form an stripe-shaped wound on the pig skin.''

Notice that the vague sentence⁶⁹``was consistent with the actual situation'' did not appear in the official report [CIB2].