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DocGKR是这么认为的，他是专家，资历都摆在那
http://www.warriortalk.com/showt ... d61a73a943ce1b9d9b0
5.56 x 45 mm U.S. M855 62 gr FMJ and 5.45 x 39 mm Russian M74 53 gr FMJ are NOT constructed in the same manner. In most cases, the 5.45 x 39 mm is LESS damaging than 5.56 x 45 mm in both laboratory and real world settings.
The Russian M74 53 gr FMJ boat-tailed bullet has a copper-plated steel jacket surrounding an unhardened steel core and a small 5 mm long empty air-space under the bullet nose. Its typical muzzle velocity is 3066 f/s. This bullet commonly exhibits very early yaw in tissue, at approximately 2.75", but no deformation or fragmentation. In both uncomplicated extremity and torso wounds, the very early yaw allows the bullet to travel sideways through the body, increasing permanent tissue destruction and temporary cavitation effects. A small punctate entrance wound is present and the exit wound may be punctate, oblong, or stellate depending on the bullet yaw angle on exit.
In the same manner, 5.56 x 45 mm bullets which exhibit early yaw, but do not fragment, for example the M955 53 gr AP, create wounds very similar to the Russian M74 53 gr FMJ. However, many 5.56 x 45 mm bullets fragment or deform, rather than just yawing. Dr. Fackler’s seminal research at the Letterman Army Institute of Research Wound Ballistic Laboratory during the 1980’s illuminated the yaw and fragmentation mechanism by which SS109/M855 and other FMJ bullets can create wounds in tissue. When 5.56 x 45 mm bullets fragment, they create wounds substantially more damaging than those resulting from the 5.45 x 39 mm. The U.S. M855/Belgian SS109 62 gr FMJ boat-tail bullet has a partial steel core surrounded by a copper jacket and a muzzle velocity of around 3034 f/s. The behavior of this bullet is very similar to that of the 5.56 x 45mm M193 bullet. The wounds created by the M193 and the M855/SS109 are nearly identical. Typically, the bullet enters the tissue, leaving a small punctate entrance wound, and then travels point forward for approximately 4.7". If the bullet leaves tissue at this point, it will leave a small punctate exit wound and will have caused minimal tissue disruption along the wound tract. If it continues to travel in tissue, it will yaw to 90 degrees at this point, flatten, and fracture at the cannelure. The flattened bullet nose remains in one piece and retains about 60% of the original bullet weight. The other 40% of the bullet behind the cannelure shatters into many fragments that can spread up to 2.75" radially away from the wound tract. These fragment each cut their own path through the surrounding tissue, multiply perforating it. Temporary cavitation then exerts its stretch effects on this weakened tissue, synergistically increasing the permanent cavity by detaching tissue pieces. Wounds in body segments thicker than 4.7" show greatly enlarged permanent and temporary cavities and can create stellate exit wounds of 3.5 to 4.7" measured form the ends opposite the skin splits. The degree of bullet fragmentation is dependent on velocity. As the range to the target increases, the striking velocity decreases, limiting bullet fragmentation. At ranges above 200 m or so, the bullet remains intact and simply yaws.
When 5.56 x 45 mm bullets fail to yaw, fragment, or deform within tissue, the results are relatively insignificant wounds, similar to those produced by .22 long rifle bullets. This is true for ALL 5.56 mm bullets, including both M855 and M193. By the same token, relatively inconsequential wounds also result when 5.45 x 39 mm bullets fail to yaw in tissue. Combat operations the past few months have again highlighted terminal performance deficiencies with 5.56 x 45 mm 62 gr M855 FMJ. These problems have primarily been manifested as inadequate incapacitation of enemy forces despite their being hit multiple times by M855 bullets. These failures appear to be associated with the bullets exiting the body of the enemy soldier without yawing or fragmenting. This failure to yaw and fragment can be caused by reduced impact velocities as when fired from short barrel weapons or when the range increases. It can also occur when the bullets pass through only minimal tissue, such as a limb or the chest of a thin, malnourished individual, as the bullet may exit the body before it has a chance to yaw and fragment. In addition, bullets of the SS109/M855 type are manufactured by many countries in numerous production plants. Although all SS109/M855 types must be 62 gr FMJ bullets constructed with a steel penetrator in the nose, the composition, thickness, and relative weights of the jackets, penetrators, and cores are quite variable, as are the types and position of the cannelures. Because of the significant differences in construction between bullets within the SS109/M855 category, terminal performance is quite variable—with differences noted in yaw, fragmentation, and penetration depths. Luke Haag’s papers in the AFTE Journal (33(1):11-28, Winter 2001) describe this problem. Unfortunately, with decreased wounding effects, rapid incapacitation is unlikely and enemy soldiers may continue to pose a threat to friendly forces. Conversely, the Hornady 75 gr open tip match bullets and Black Hills loaded 77 gr Match King open tip match bullets have been working fairly well.
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发表于 2014-7-1 07:35
楼主
发表于 2014-7-1 11:41