Glossary of Firearms Terms - E

E

• electronic firing: The use of an electric current to fire a cartridge, instead of a percussion cap. In an electronic-fired firearm an electric current is used instead to ignite the propellant, which fires the cartridge as soon as the trigger is pulled.

• eye relief: For optics such as binoculars or a rifle scope, eye relief is the distance from the eyepiece to the viewers eye which matches the eyepiece exit pupil to the eye's entrance pupil. Short eye relief requires the observer to press his or her eye close to the eyepiece in order to see an unvignetted image. For a shooter, eye relief is an important safety consideration. An optic with too short an eye relief can cause a skin cut at the contact point between the optic and the eyebrow of the shooter due to recoil.

• expanding bullet: An expanding bullet is a bullet designed to expand on impact, increasing in diameter to limit penetration and/or produce a larger diameter wound. The two typical designs are the hollow point bullet and the soft point bullet.

• extractor: A part in a firearm that serves to remove brass cases of fired ammunition after the ammunition has been fired. When the gun's action cycles, the extractor lifts or removes the spent brass casing from the firing chamber.