Grease Ring
Definition
A grey-to-black discolouration at the outer margin of the entry wound's abrasion collar, caused by lubricant and metal fouling on the bullet surface being wiped off during skin penetration. Distinguishable from soot (which is heavier and more concentrated and only seen at close-range firing).
- Appearance
- Grey-to-black discolouration at the outer margin of the abrasion collar
- Composition
- Bullet lubricant and metal fouling wiped off the bullet surface during skin penetration
- Key distinction from soot
- Water-insoluble deposit at the wound margin; soot is heavier, more concentrated, and only appears at close range
Common questions
What is a grease ring on a gunshot wound?+
A grease ring is a grey-to-black discolouration at the outer margin of an entry wound's abrasion collar. It forms when lubricant and metal fouling on the bullet surface are wiped off as the bullet penetrates the skin.
How do you tell a grease ring apart from soot?+
Grease rings appear at the outer margin of the abrasion collar and are water-insoluble. Soot is heavier, more concentrated, and only appears in close-range wounds. Their position, colour, and water-solubility differences make them distinguishable.
Why does a bullet leave a grease ring as it enters skin?+
The lubricant and metal particles on the bullet's surface rub off during penetration and deposit at the edge of the abrasion collar.
Related terms
- Abrasion Collar
- The rim of abraded, dried skin surrounding a gunshot entry wound, produced by the bullet stretching the skin inward before perforation. Width...
- Blow-Out Exit Wound
- A large, ragged exit wound with radiating lacerations produced when the bullet retains high residual kinetic energy at exit and the skin...
- Shored Exit Wound
- An exit wound in which the exiting skin is braced against a hard surface at the moment of exit, preventing eversion and...
- Contact Stellate Wound
- Entry wound morphology at hard-contact muzzle-to-skin distance over bone: central perforation with radiating linear lacerations caused by discharge gas expanding laterally beneath...
- Muzzle Imprint
- A patterned contusion or abrasion left on skin by the muzzle face of the weapon in hard-contact wounds. In revolvers, the cylinder-face...
- Permanent Cavity
- The lasting wound channel produced by the bullet's direct crushing and laceration of tissue. Diameter approximates expanded projectile diameter. At handgun velocities,...
- Secondary Missile
- A bone fragment or other dense internal body component that is driven by bullet impact to become a projectile in its own...
- Stippling (Tattooing)
- Discrete punctate abrasions or haemorrhages around an entry wound from individual unburned propellant granules embedding in the epidermis at intermediate range. Unlike...
- Temporary Cavity
- The transient radial tissue displacement produced by a bullet's passing. Caused by the transfer of kinetic energy to surrounding tissue via compression...
Explained in these topics
- Firearm Entry and Exit Wounds: The Medico-Legal ReadingA grey-to-black deposit at the outer margin of the abrasion collar, from barrel lubricant and metal fouling being wiped off the bullet as it passes through ski...
- Wound Ballistics: Entry Wounds, Exit Wounds and CavitationA grey-to-black discolouration at the outer margin of the entry wound's abrasion collar, caused by lubricant and metal fouling on the bullet surface being wipe...