Cannelure /(kăn"nē̇*lū̇r)/

Can·ne·lure

Cannelure

n.
  1. A groove in any cylinder; specif., a groove around the cylinder of an elongated bullet for small arms to contain a lubricant, or around the rotating band of a gun projectile to lessen the resistance offered to the rifling. Also, a groove around the base of a cartridge, where the extractor takes hold. (Mil.)