刮痕

• The tiny scratches on a bullet as it explodes down a barrel bear distinctive marks for every weapon ; experts can pinpoint which revolver or rifle fired a shot that killed . in recent years , uniformed officers have been issued with . 38 heavy barrel revolvers , a weapon better designed for self - defence against dangerous gunmen
  当子弹经过枪管发生爆炸时，子弹便会刻上细小刮痕，成为个别枪械的独特记号；专家可准确地指出致命的子弹是从那一枝左轮手枪或来福枪发射的。