firearm related evidence-Mark

Question 1

cartridge cases

Answer 1

marks can be striated which are produced by lateral movement of the cartridge case against the firearm or impressed when the firearm impacts the cartridge case with force

Question 2

impression evidence may come from:

Answer 2

deliberate marks left by the manufacturer
action of a weapon in general
chamber
breech face
firing pin
shear marks
extraction mechanism
extraction port

Question 3

firing pin hole

Answer 3

when a cartridge case is forced backwards from recoil the primer imbeds itself in the firing pin hole

as the slide of the pistol starts to recoil, the barrel will drop slightly as the action opens

the dropping barrel forces the cartridge case to move down slightly and when this happens the lower edge of the embedded primer is sheared downward and out of the firing pin hole

Question 4

firing pin drag marks

Answer 4

when the firing pin springs forward to stroke the primer of a cartridge, it may remain slightly forward and embedded in the primer

certain barrels drop dow slightly as recoil is forcing the action open

cartridge case drops with the barrel causing the nose of the protruding firing pin to drag across the primer as it leaves the firing pin impression