General Rifling Characteristics

Gross impressions visible to the naked eye are made in the surface of bullets while in hard contact with the bore of the barrel. The clockwise or counterclockwise grooves inside a barrel result in groove impressions (higher areas) on the surface of a fired bullet. The areas between the grooves inside a barrel (lands) result in

land impressions (lower areas) on the surface of a fired bullet. These gross impressions can be associated with a number of brands and models of firearms of certain classes. In the field of firearms identification, these class characteristics are called general rifling characteristics (GRC).

Although GRCs cannot identify a specific firearm, they are a useful investigative tool. They can provide invaluable lead information to investigators concerning the type of firearm.

Categories

The categories of general rifling characteristics are

• caliber (bore diameter),
• number of land and groove impressions,
• direction of twist,
• land and groove impression dimensions.

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