Left-Hand Twist (LHT)
Definition
Rifling that spirals counterclockwise toward the muzzle. The defining house convention of Colt Manufacturing Company and of the Lee-Enfield rifle family.
- Direction
- Counterclockwise toward the muzzle
- Associated makers
- Colt, Lee-Enfield family
- Opposite
- Right-hand twist (most common)
- Use
- Class characteristic in firearm identification
Common questions
Why does twist direction help identify a firearm's make?+
Rifling direction is fixed by the manufacturer's tooling and stays consistent across a maker's production, so observing spiral direction on a recovered bullet narrows the list of possible source firearms before finer individual toolmark comparison begins.
Is left-hand twist rare compared to right-hand twist?+
Yes, most manufacturers cut right-hand twist rifling, so a left-hand twist bullet or barrel meaningfully narrows the pool of candidate makes, with Colt and Lee-Enfield being well-known examples of the minority convention.
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...
- 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;...
- Rate of Twist
- The barrel length required for the rifling to complete one full helical revolution, expressed as a ratio (e.g. 1:9 means one complete...
- 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.