Rate of Twist
Definition
The barrel length required for the rifling to complete one full helical revolution, expressed as a ratio (e.g. 1:9 means one complete rotation per nine inches of barrel).
Related terms
- BKA
- Bundeskriminalamt, the German Federal Criminal Police Office, which operates the German GRC and ballistic identification database feeding the European EBIS network.
- CFSL
- Central Forensic Science Laboratory: a central government lab operating under DFSS. India has CFSLs at New Delhi, Hyderabad, Chandigarh, Kolkata, Pune, Guwahati,...
- General Rifling Characteristics (GRC)
- The class-level barrel properties (land count, groove count, land width, groove width, twist direction, twist rate) that allow a fired bullet to...
- Grooves
- The recessed channels cut into a rifled barrel between the lands. They create raised land impressions on a fired bullet's surface.
- Lands
- The raised ridges of a rifled barrel. Lands engrave groove impressions into the surface of a passing bullet. They are the harder...
- Left-Hand Twist (LHT)
- Rifling that spirals counterclockwise toward the muzzle. The defining house convention of Colt Manufacturing Company and of the Lee-Enfield rifle family.
- NABIS
- National Ballistics Intelligence Service; the UK police intelligence service that maintains a national headstamp and firearm reference collection and coordinates ballistic intelligence...
- Polygonal Rifling
- A rifling form that uses a rounded hexagonal or octagonal bore profile instead of discrete lands and grooves. Characteristic of Glock barrels;...
- Right-Hand Twist (RHT)
- Rifling that spirals clockwise toward the muzzle when viewed from the breech. Used by the majority of the world's firearm manufacturers.
Explained in
- Rifling Characteristics: Lands, Grooves, Twist DirectionThe barrel length required for the rifling to complete one full helical revolution, expressed as a ratio (e.g. 1:9 means one complete rotation per nine inches...