Important Terms

Gauge: A unit of measurement of a shotgun bore. It is derived from the number of round lead balls of the same diameter that weigh one pound. In other words, a lead ball the same diameter as a 12 gauge bore is 1/12th of a pound. The .410 is the only exception-measured in the diameter of the projectile.

Dram Equivalent: A measurement to compare the velocities in modern smokeless shotshells. It is derived from the measurements used in blackpowder where a dram is a measurement of volume of powder in the charge.

Shot size: A numerical (or letter) designation for the average diameter of pellet. The number is determined using the formula (17-number designation)/100. For example, #5 shot is .12 inches (17-5)/100.

Slug: A shotgun slug is a single projectile or bullet that can be loaded in shotshells. There are two main types of slug:
  • Rifled or “Foster Slug” like the Tru-Ball® designed for smoothbore shotguns
  • Sabot slug like Barnes® Expander® designed for fully rifled barrels

Sabot: Derived from the French work for shoe, a sabot is generally a plastic sleeve that encases a smaller bullet, enabling the projectile to be fired from a larger bore firearm.

Non Toxic Shot: Shotshell pellets made from steel, tungsten and other materials approved by the USFWS for hunting waterfowl.

Choke: Constriction in the shotgun's muzzle is referred to as choke. The level of constriction affects how wide a shot gun pattern spreads out.