The penetration of various materials can be of great assistance in the investigation of shooting incidents. It is also of considerable general interest if for no other reason than to show how often the movie makers and novel writers make appalling blunders.
In the past, one of the standard tests performed to assess bullet and cartridge performance was the penetration of pine boards of various thicknesses. This, as with any other type of penetration test, is plagued with inaccuracies.
Many factors, including the moisture content, knot content, tree age and even the separation of the boards, can give rise to highly variable results. Other than for general interest, this type of test is of little use in the scientific examination of firearms-related situations.
For the sake of interest, some indicators of the penetrative powers of various types of ammunition follow:
0.22" Lead air gun pellet requires a minimum of 250 ft/s velocity to penetrate fresh human skin.
0.177" Lead air gun pellet requires a minimum of 300 ft/s velocity to penetrate fresh human skin.
0.22" Lead air gun pellet at 450 ft/s will make a hole in, but not penetrate ■4" plate glass.
0.22" Lead air gun pellet at 600 ft/s will penetrate 4' plate glass.
Steel BB (0.170" ball bearing) at 200 ft/s will make a hole, but will not penetrate 4" plate glass.
Steel BB or 0.177" lead pellet at 200 ft/s will detach part of the coloured portion (iris) of a human eye leaving what appears to be a second pupil.
Steel BB or 0.177" lead pellet at 450 ft/s will burst a human eye.
0.177" Steel air gun dart will penetrate to shank, in skin, at 120 ft/s.
158 gr 0.38" Special plain lead bullet will generally not penetrate the outside skin of a car body.
158 gr 0.357" Magnum semi-jacketed bullet will penetrate outside skin of car door and sometimes just penetrate the inside skin.
125 gr 9 mm PB fully jacketed bullet will generally penetrate both skins of a car door.
158 gr 0.38" Special plain lead bullet will only penetrate one side of a human skull.
158 gr 0.38" Special plain lead bullet will generally not exit from a human body.
158 gr 0.38" Special + P and 0.357" Magnum semi-jacketed bullets will penetrate both sides of a human skull.
0.38" Special + P, 158 gr non-expanding bullet will, unless it strikes a bone, pass straight through a human body.
Virtually all calibres (excepting air weapons) will penetrate the tread or side wall of a motor vehicle tyre.
Penetration of 7" pine boards for various pistol calibres:
0.22" LR five boards
0.32" ACP five boards
0.38" S&W revolver five boards
0.38" Special seven boards
9 mm PB pistol nine boards
0.45" ACP seven boards
Illustrative penetration capabilities of a 30-06 full -jacketed rifle bullet at a velocity of 2700 ft/s and at a range of 200 yd:
1" of armour plate 7" of gravel 4.5" of brick 4" of concrete 32" of oak wood 6.5" of dry sand 7" of moist sand 26" of loam 24" of clay 19" of loose earth 60" of 1" pine boards
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