Contents
Introduction
In an effort to conceal the provenance of stolen guns, serial numbers are often destroyed using various techniques. These techniques include filing or grinding, peening, over-stamping, centre striking, drilling, and welding. The methods involve physically altering or obliterating the original serial number to make it unidentifiable. This deceptive practice is often accompanied by stamping a new number or using additional materials like lead solder or weld material to fill the void left by the removed number. The visual representation of these techniques provides insight into the extent of alteration required to render the original serial number untraceable.
Different Types of Tool Marks
Methods for Removal of Serial Numbers
Filing or grinding
This method involves removing the number by hand filing or grinding with a high-speed carborundum grinding wheel. A new number being overstamp after refining frequently follows this.
Peening
This process entails a simple round strike to the surface in order to entirely obscure the number.
Over-stamping
Over-stamping is the process of stamping a new number on top of the previous set of numbers. When dealing with curved-surfaced numerals, namely 2, 3, 5, 6, 9, and 0, the 8 imprint is the most frequently selected option. The apparent choice for numerals featuring linear surfaces, such as 1 and 7, is the 4 stamps. Serial numbers that contain an unfair distribution of ‘8’ or ‘4’ digits should be regarded with scepticism.
Restoration of Erased Markings on Metal Surfaces
Centre striking
Using a pointed strike, center-punching destroys the entire numbered surface.
Drilling
Using a drill, completely remove the number and the adjacent metal. In order to fill the remaining cavity, lead solder or weld material is typically utilized.
Forensic Examination of Firearms
Welding
Welding involves applying heat to the surface using an oxyacetylene welder or an arc welder until the metal flows.
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