Polygonal Rifling
Definition
A rifling form that uses a rounded hexagonal or octagonal bore profile instead of discrete lands and grooves. Characteristic of Glock barrels; produces shallower engraving on the bullet.
- Bore profile
- Rounded hexagonal or octagonal, no discrete lands/grooves
- Common manufacturer
- Glock
- Effect on bullet
- Shallower engraving marks
Common questions
Why does polygonal rifling complicate bullet comparison?+
The shallower, smoother engraving leaves fainter individual striae than conventional land-and-groove rifling, which reduces the amount of detail an examiner has to work with for a toolmark match.
Is polygonal rifling unique to Glock?+
No. Glock popularised it, but other manufacturers, including Heckler & Koch and Steyr pistols, also use polygonal bore profiles.
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...
- 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.