Rifling
Definition
The helical groove pattern cut into a firearm barrel that imparts spin to the bullet, stabilising it in flight. Rifling lands and grooves leave corresponding marks on a fired bullet that are characteristic of that specific barrel.
- Purpose
- Imparts spin to the bullet for gyroscopic stability in flight
- Forensic signature
- Lands and grooves leave characteristic marks on fired bullets unique to each barrel
- Found in
- Most pistols and rifles; absent in smoothbore firearms like shotguns
Common questions
What is rifling and why do gun barrels have it?+
Rifling is a pattern of helical (spiral) grooves cut into the inside of a firearm barrel. The raised metal between the grooves is called lands. When a bullet travels through the barrel, the lands and grooves spin it like a football, which keeps it stable and on course during flight. Smoothbore firearms like shotguns have no rifling at all.
How does rifling help forensic investigators?+
Each barrel's rifling pattern is unique, like a fingerprint. When a bullet is fired, the lands and grooves leave characteristic marks on its surface. Examiners can match these marks to the specific gun that fired it, making rifled bullets powerful evidence in investigations.
What does notation like '5R' or '6L' mean on guns?+
The number tells you how many lands and grooves are in the barrel. The letter shows the twist direction: R for right-hand twist (most common) and L for left-hand twist. So '5R' means the barrel has 5 lands and 5 grooves, spiraling to the right.
Related terms
- Comparison Microscope
- Two compound microscope bodies connected by an optical bridge that presents one half of each body's image in a single split eyepiece...
- AFTE Conclusion Scale
- Association of Firearm and Tool Mark Examiners scale: identification, inconclusive (subdivided A, B, C), elimination, unsuitable. The court-admissible vocabulary.
- Ammunition
- The cartridge assembly fired by a firearm. Comprises case, primer, propellant and projectile. Defined under Section 2(1)(b) of the Arms Act 1959...
- Bore / Caliber
- Bore is the internal diameter of the barrel. Caliber is that diameter expressed in inches (.32,.38) or millimetres (9 mm, 7.62 mm)....
- Breech Face
- The forward surface of the bolt, slide, or breech block that seals the chamber and contacts the cartridge case head during firing....
- Cartridge
- The complete round of ammunition: case plus primer plus propellant plus projectile, assembled as a single unit for breech loading.
- Cartridge Case Markings
- Impressions left on a fired cartridge case by the breech face, firing pin, extractor, and ejector of the firearm. Like rifling marks...
- Class Characteristics
- Features deliberately or systematically imparted to a group of items by design or manufacture, such as the calibre of a bullet, the...
- Firearm
- A barrelled weapon that launches a projectile by the rapid expansion of gas from a confined burning propellant. Includes handguns, rifles and...
- IBIS
- Integrated Ballistics Identification System: an image-based database platform used by multiple countries to store and compare fired cartridge cases and bullets from...
- IBIS / NIBIN
- Integrated Ballistic Identification System (Forensic Technology Inc., Canada) and Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF)'s National Integrated Ballistic Information Network....
- Individual Characteristics
- Surface features on a fired bullet or cartridge case that arise from random or unique events (tool wear, corrosion, service damage) and...
Explained in these topics
- Ballistics Evidence in Wildlife PoachingThe helical groove pattern cut into a firearm barrel that imparts spin to the bullet, stabilising it in flight. Rifling lands and grooves leave corresponding m...
- Firearms: Types, Classification, Ammunition and CompositionsSpiral grooves cut into the bore of a firearm barrel to spin the bullet for gyroscopic stability. Lands are the raised metal between grooves. Smoothbore arms (...
- Forensic Examination of Firearms, Bullets, Shells and CartridgesHelical lands (raised) and grooves (cut) inside a rifled barrel. Imparts spin to the bullet for gyroscopic stability. Notation like 5R or 6L means lands and gr...