Center fire firing pin marks

Firing pins used in center fire guns frequently have a considerable degree of individuality also. The ends often have concentric rings made by the cutting tool that formed them and these are impressed in facsimile on the copper at the bottom of the firing pin impression. Inasmuch as these rings are different for all firing pins and since they can often be matched under the comparison microscope with their counterparts on test shells, they are always looked for. Some firing pins have ends that are flat, others are blunt and rounded, while still others are highly tapered, and some are even pointed. Then too, firing pins develop individuality because of wear and chipping. Markings due to these causes, having a high degree of individuality, are frequently encountered. The chance that two firing pins would chip in precisely the same way is very remote indeed. The angle at which a firing pin strikes the primer should be noted. The firing pin in a revolver usually, though not always, strikes at an angle, since the hammer to which it is attached or of which it is an integral part moves through an are. In some revolvers there is an independent firing pin which moves forward when struck by the hammer and strikes the primer vertically (to the surface).

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