05-29-2011, 03:17 AM
Joe, while going through my files today, I came across this bit:
"[The] NATO standard, mild steel test plate...defines the penetration performance required of NATO rifle ammunition. It simulates the penetration deemed necessary to produce a lethal wound against enemy personnel protected by steel helmets and body armor, and to penetrate reasonable cover. The plate is 3.5mm (.138") thick, of AISI 1010 or 1020 equivalent mild steel of Rockwell hardness B55-70. Acceptance standards for 5.56mm NATO ammunition require all rounds (except tracers) to perforate this plate at 570 meters (623 yds.) under standard atmospheric conditions."
C. E. Harris, "How Does NATO's New 5.56mm Round Measure Up?", American Rifleman, May 1982, pp. 77-78.
Does this help?
"[The] NATO standard, mild steel test plate...defines the penetration performance required of NATO rifle ammunition. It simulates the penetration deemed necessary to produce a lethal wound against enemy personnel protected by steel helmets and body armor, and to penetrate reasonable cover. The plate is 3.5mm (.138") thick, of AISI 1010 or 1020 equivalent mild steel of Rockwell hardness B55-70. Acceptance standards for 5.56mm NATO ammunition require all rounds (except tracers) to perforate this plate at 570 meters (623 yds.) under standard atmospheric conditions."
C. E. Harris, "How Does NATO's New 5.56mm Round Measure Up?", American Rifleman, May 1982, pp. 77-78.
Does this help?