Deburr - To remove burrs or roughness sometimes left on case mouth edge by trimming operation. See chamfer.


Decap or Deprime - To remove or eject a primer from its primer pocket. Usually done by the decapping pin in the sizing or expanding operation.


Deterrent Coating - A chemical coating applied to the surface of powder granules to control the burning characteristics of the base powder. Aptly described as a "temporary fire-proofing" of a powder kernel.


Die - In handloading, a tool to form or reform cases or bullets by cold-working, or to seat bullets.


Double-base Powder - Nitrocellulose (smokeless) propellant that uses nitroglycerine as the plastisizer.


Drag - see air resistance


Dram Equivalent - In shotshells, a term used to indicate that a charge of smokeless powder produces the same velocity as a given number of drams of black powder. Thus, a 3 dram equivalent load has a charge of smokeless powder that gives the same velocity as a similar load charged with 3 drams of black powder. One dram equals 27.3 grains.


Drift - In exterior ballistics, the deviation of a projectile from the line of departure due to its rotation or spin. Also commonly but incorrectly applied to the effects of wind. See wind deflection.


Drop - The distance a projectile falls due to gravity, measured or calculated from the line of departure as it travels downrange. Must be corrected for difference between line of sight and line of departure. Drop is normally reported assuming a horizontal barrel.


Duplex Load - A dangerous condition that uses two different powders in loading the same cartridge. There is little or no advantage to duplex loading in small arms and results are unpredictably dangerous.