MV is king up close M193 pentrates better (200 meters and less). Both have similar terminal effects and yaw/fragment (M193) or shed jacket (M855) within 150 meters for 16" or 200 meters for 20" barrels. Beyond 200 meters both tend to just drill .22 cal holes unless they hit bone then they might yaw but likely won't fragment. If you need to pentrate a helmet at 800 meters then the M855 is the round to use.

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