Letter U Firearms Glossary

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Underbolts

A sliding bar, running longitudinally through the watertable of a break-open side-by-side gun's action, with openings through which the lumps of the barrels pass when the gun is closed. Under spring tension, this bar moves forward when the opening control is released and its two locking surfaces engage complementary slots (bites) in the rear of the two barrel lumps. Originally operated by a hinged tab in front of the trigger guard. Now invariably operated by a cam from Scott's [toplever] spindle. Most modern side-by-side guns lock closed in this manner.

Underhammer

A type of lock in which the hammer pivots in a vertical arc, striking the nipple on the underside of the barrel. Since the nipple's flash channel goes straight into the powder at the breech end of the barrel, ignition time is very fast. For this reason, and because it gets the hammer out of the way, underhammer locks are commonly used on muzzleloading benchrest rifles which are used for target shooting, and where accuracy is the goal.

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.

Underwater Firearm

A firearm specially designed for use underwater.

Upset Forging

A process that increases the diameter of a workpiece by compressing its length.


14 Other Firearms Definitions You Need To Know


High-Capacity Magazine

An inexact, non-technical term indicating a magazine holding more rounds than might be considered "average.".

Choke Tubes

Short, interchangeable cylinders, of subtly different internal tapers, that screw into a threaded recess at the muzzle of a shotgun. By inserting different choke tubes, one can alter the shot pattern thrown by the gun.

Point of Impact

The point where the projectile from a firearm hits.

CCL

Abbreviation for Concealed Carry License.

LCI

Abbreviation for Loaded Chamber Indicator

Second Amendment

The second article in the United States Bill of Rights which states, "A well regulated militia being necessary for a free state, the right of the people to keep and bear arms shall not be infringed."

Over Travel

If the trigger is able to continue moving to the rear after the shot has fired, the trigger is said to over-travel.

Youth Stock

A short stock, often ideally sized for teenagers, average-sized adult women, and small-statured adult males.

OFF

Oregon Firearms Federation. OFF is a Pro-Gun rights group based in Oregon and was founded in 1998.

Gas Port

A small hole in the barrel of a gas-operated firearm through which expanding gases escape to power the autoloading system.

Riding the Slide

Racking the slide incorrectly by allowing your hand to rest upon the slide as it moves forward during the loading procedure. Riding the slide is a common cause of misfeeds and other malfunctions.

Fulminate Of Mercury

A highly sensitive explosive used as a primer compound.

Striker

In a handgun that does not have a hammer, the striker is a linear driven, spring loaded cylindrical part which strikes the primer of a chambered cartridge. The striker replaces both the hammer and firing pin found in hammer driven pistols.

Recoil Compensator

A device fitted inside the buttstock of a heavily-recoiling gun or rifle, usually containing mercury and a valve. As the gun recoils, the mercury is displaced temporarily, increasing the duration, and thus diminishing the perceived impact of the recoil. The added half-pound of weight doesn#39;t hurt either.