Letter U

The Definition of Underlug

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Underlug

The locking lugs on a break-action firearm that extend from the bottom of the barrels under the chamber(s) and connect into the receiver bottom.


19 Other Firearms Definitions You Need To Know


Drop-Box Magazine

An extra-deep magazine typical of large calibre rifles for dangerous game. The line of the underside of the wrist does not carry straight forward as with ordinary rifles. Rather the rear of the magazine aligns more towards the center of the forward edge of the triggerguard, typically allowing at least one extra cartridge to be carried.

Barrel

A tube, usually metal, through which a controlled explosion or rapid expansion of gases are released in order to propel a projectile out of the end at a high velocity. It is the tube through which the bullet or shot travels. The barrel serves the purpose of providing direction and velocity to the bullet.

Hinge Pin

A short cylindrical rod of hardened steel running laterally near the front of the bar of a break-open gun's action around which the barrel hook revolves when the gun is opened. Over the decades, this pin and its complimentary hook can wear and a gun can sometimes "shoot loose" or "come off the face." The proper cure for this condition is to replace the hinge pin with a new one, slightly oversized, to compensate for wear on both itself and on the barrel hook.

Collimator Sight

Also known as collimating sight or occluded eye gunsight, a Collimator Sight is a type of optical "blind" sight that allows the user looking into it to see an illuminated aiming point aligned with the device the sight is attached to regardless of eye position (parallax free). The user can not see through the sight so it is used with both eyes open while one looks into the sight, with one eye open and moving the head to alternately see the sight and then at the target, or using one eye to partially see the sight and target at the same time.

Center Of Mass

For self-defensive shooters, Center Of Mass (COM) represents the area of an attackers torso within which the most vital organs are likely to be disrupted by a gunshot. Shooting to COM is considered the most expedient way to stop an assailant from continuing threatening behavior.

DAO

Abbreviation for Double Action Only. Is a type of firearm in which the firing mechanism cannot be cocked in a single-action stage. Firing always occurs as a double-action sequence where pulling the trigger both cocks and then fires the gun.

Overshoot

A term used in artillery to indicate a projectile impact beyond the designated target.

Erosion

The wearing away of a barrel's metal surface by a bullet or shot charge or by the heat of powder gases.

Lands

In the rifling of a bore, the uncut portions of the barrel's inner surface left after the rifling grooves have been cut into the metal. In other words, the raised portion of rifling.

Snub-Nose

Slang word for short barreled revolver.

Federal Assault Weapons Ban

Part of the Violent Crime Control and Law Enforcement Act of 1994. It produced a 10-year federal ban on the manufacture of new semi-automatic assault weapons with certian specifications. Firearms with specific features were defined as assault rifles. Including the AR-15, certain versions of the AK-47, the TEC-9, the MAC-10 and the Uzi, several of which had become the preferred weapon of violent drug gangs. The act also bans large-capacity ammunition magazines, limiting them to 10 rounds. The law did not apply to weapons that were already in legal possession.
Because this law was not renewed by congress in 2004, the ban was lifted.

Birdshot

A type of shotgun ammunition which uses very small pellets with individual projectiles of less than .24" in diameter designed to be discharged in quantity from the shotgun. The size of the shot is given as a number or letter-- with the larger number the smaller the shot size. It is so named because it is most often used for hunting birds. The finest size generally used is #9 which is approximately .08" in diameter and the largest common size is #2 which is approximately .15"

Crisp Trigger

A trigger that breaks (to release the hammer) easy.

Cant

To tilt a gun to one side or the other, complicating sighting considerably. Can cause material loss of accuracy, particularly with a rifle at longer ranges. Some better long range target rifles are equipped with Spirit Level sights to help control canting.

Lock Speed

The same as Lock Time

Pistol Grip

The handle on a pistol. Can also refer to a vertical grip behind the trigger on a rifle.

Mauser Safety

A small lever mounted to the cocking piece of a Mauser 98 action (and its copies such as the Springfield 1903), rotating on a longitudinal axis from left (Fire), up to the top (Safe, but allowing bolt movement), and over to the right (Bolt and firing pin locked Safe). While commendable for locking the firing pin instead of just the trigger, its up-and-over arc of operation requires a scope to be mounted awkwardly high. Paul Mauser is not to be blamed; when his safety was developed, telescopic sights were in such infancy as not to be worthy of mainstream consideration.

Assault Rifle

Assault Rifles and Assault Weapons do not exist. The terms Assault Rifle and Assault Weapon are made up terms by the anti-gun lobby to describe black rifles with forward grips that you might see in the movies like an AR-15 or an AK-47. Assault Rifles do not exist because a gun cannot assault anything, they are machines that need to be operated by a person.

Rail

A feature on some guns which allows various aftermarket accessories to be attached the firearm such as flashlights or lasers. On pistols, if equipped, the rail is on the underside of the frame below the barrel. On rifles, a rain can be found above or below the barrel, with AR type rifles, the forestock can be made of rails allowing all kinds of attachments in various positions.