Letter I Firearms Glossary

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Improved Cartridge

A wildcat cartridge that is created by straightening out the sides of an existing case and making a sharper shoulder to maximize powder space. Frequently the neck length and shoulder position are altered as well. The caliber is NOT changed in the process.

Improvised Firearm

A firearm manufactured by someone who is not a regular maker of firearms.

Inertia Firing Pin

A firing pin which moves freely forward and backward in the breechblock.

Inletting

The process of carving out recesses in wooden stocks with precision, using gouges, chisels and scrapers to accept the steel components of a firearm.

Integral Lock

A built in lock that may prevent the firearm from being fired.

Intercepting Sear

A second sear, poised just behind a second notch in the hammer. It is possible that when a cocked firearm is dropped or sharply jarred, a single sear could jump out of its notch and the hammer could fall, firing the gun accidentally. In this event, an intercepting sear would engage before the hammer could fall completely, preventing an accidental discharge. On a gun with intercepting sears, only by pulling the trigger are both sears moved out of the way simultaneously, allowing the gun to fire. Intercepting sears are usually found on better sidelock actions. They are sometimes found on best boxlocks, and can be recognized by an extra screw behind the action fences, in addition to the usual two screws (or pins) along the lower rear of the receiver.

Internal Safety

A safety which is placed within the gun and is not accessible to the user. Internal safeties are generally designed to prevent unintentional discharges when the gun is dropped or mishandled.

Internal Trigger Lock

A internal locking device built into a firearm, usually operated with a key, to render it unable to be fired. A good example of a internal trigger lock are the ones found on the semi-automatic pistols manufactured by Bersa.

Interrupted Thread

A screw with about half of its threading removed in longitudinal sections. Often used at the breech end of a takedown firearm's barrel. When the barrel's interrupted female threads are inserted into the receiver's complementary interrupted male threads, only a partial rotation is necessary for assembly rather than many full turns.

Iron Sights

The mechanical sighting system which usually comes with the firearm made of metal with no optics.

Island Rear Sight

A rear barrel sight base, more articulated than having the sight simply dovetailed into the barrel, but not requiring as much gunsmithing as having it mounted onto a proper quarter-rib.

Isosceles Stance

There are two basic variants of the Isosceles stance, the Traditional Isosceles and Modern Isosceles stance. In both Isosceles stances, the feet parallel pointing toward the target and are roughly shoulder width apart. Both arms are stretched almost equally forward with the gun centered forward, creating the triangular shape which gives the stance its name.


7 Other Firearms Definitions You Need To Know


Misfire

The condition of a cartridge not firing when an attempt to fire it is made. It can be caused by either a defective cartridge or a defective firearm. The term is frequently misused to indicate a Negligent Discharge of a firearm.

Blank

A type of cartridge for a firearm that contains gunpowder but no bullet or shot. When fired, the blank makes a flash and an explosive sound (report). Blanks are often used for simulation (such as in historical reenactments, theatre and movie special effects), training, and for signaling (see starting pistol). Blank cartridges differ from dummy cartridges and snap caps, which are used for training or function testing firearms; these contain no primer or gunpowder, and are inert.

Group

A set of holes in a target left by a succession of bullets fired from the same rifle or handgun, using the same ammunition and sight setting. Fired (within the limits of one's marksmanship ability) to determine the inherent accuracy of the rifle/ammunition combination, and to aid in the proper adjustment of the sights.

Elevation

The setting on the sights of a firearm that controls the vertical placement and the altitude above mean sea level. This is important for long range precision shooting because the air density changes with elevation and affects the path of the bullet.

Stalking Safety

A safety catch fitted to a hammer gun where a sliding bar moves into a slot in the inner wall of the hammer base, locking it in place in the cocked position. The safety can then be released silently by sliding the tab, avoiding the game-startling sound of the hammer cocking.

Boattail

The tapered rear end of a bullet. This design is used to increase ballistic efficiency at long range.

Traditional Isosceles

In the Traditional Isosceles stance, Both arms are stretched almost equally forward with the gun centered forward. The knees are straight or only slightly flexed, and the entire body is upright and parallel to the target. This is an acceptable range stance provided recoil control is not an issue and you don't need to make rapid follow-up shots. However, if you are practicing for self-defense, you will probably want to use the Modern Isosceles stance stance instead.