Letter O

The Definition of OTM

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19 Other Firearms Definitions You Need To Know


Smooth Bore

A barrel without rifling. Smooth bore barrels are commonly used in shotguns and in large bore artillery that fire fin stabilized projectiles.

Eye Dominance

Although we have two eyes for depth perception and for spare parts, there is a natural tendency for one eye (the master eye) to take precedence over the other, regardless of the relative visual acuity of each eye. It is a fortunate condition when the eye on the side of the shoulder where one is comfortable mounting a gun is also the dominant eye.
To test for eye dominance:

Pick out a small object several feet away. With both eyes open, center your right index finger vertically over the object. Close your right eye. If your finger appears to jump to the right, you are right eye dominant. Then open your right eye and close your left eye. If your finger remains in position in front of the object, you have confirmed your right eye dominance. Alternatively, if in the above test, upon closing your right eye your finger remains in position covering the object, you are left eye dominant. If you close your left eye instead and your finger appears to jump to the left you have confirmed your left eye dominance.
Eye dominance problems can be treated with
1. A severely-cast, crossover stock to bring the dominant eye in line with the gun's line of sight, 2. A patch over the dominant eye, or just a small piece of frosty Scotch tape on shooting glasses intercepting the dominant eye's line of sight, 3. Fully or partially closing the dominant eye, or 4. Learning to shoot from the dominant-eye shoulder.
While less convenient, methods that retain the use of both eyes better preserve the ability to perceive depth in three-dimensional space, a great benefit in wingshooting.

Hook

A concave, semi-cylindrical surface cut into the forward lump of a barrel set of a break-open firearm which revolves about the hinge-pin when the gun is opened.

Frontstrap

Front, metal, part of a handgun's grip, which together with the backstrap, provides a mounting frame for the grip panels.

Back Bored

A shotgun barrel that has a bore diameter increased beyond standard specifications, but less than the SAAMI maximum. Done in an attempt to reduce felt recoil, improve patterning, or change the balance of the shotgun.

NRA

The National Rifle Association. This organization coordinates shooting events on a national level, provides firearms training to civilians and law enforcement, fights restrictive firearms legislation and supports the constitutional right of law abiding citizens to own and carry firearms.

Firing Line

A line, either imaginary or marked, from which people shoot their firearms down range.

Makarov

The Soviet Union's standard military and police side arm from 1951 to 1991 replacing the Tokarev TT-33 semi-automatic pistol and the Nagant M1895 revolver. Designed by Nikolay Fyodorovich Makarov, it is a blowback operated semiautomatic pistol which fires the 9x18mm Makarov cartridge, and holds 8 rounds in the magazine.

Cross Dominant

This means a shooter who is right-handed but left-eyed, or left-handed and right-eyed.

Trajectory

The arc described by a projectile (or a load of shot) after it exits the muzzle of a firearm. Falling objects accelerate downwards at a rate of 32 feet per second, per second. The faster a projectile travels, the greater the distance it can cover in a given time before dropping too far. Hence, the higher the velocity of a bullet, the flatter the trajectory it will achieve.

Hand-Detachable Locks

The firing mechanism of a break-open gun which may be removed for inspection or cleaning without the use of tools. The release latch may be plainly visible or concealed. A feature typically seen on sidelock guns but also on the Westley Richards "droplock" boxlock action.

Globe Sight

A front sight assembly, primarily for target rifles, consisting of a tube, housing interchangeable beads and blades. The tube guards against imperfect aiming due to sight pictures influenced by reflections.

Factory Ammo

Ammunition that has been assembled by a commercial vendor of ammunition and sold in retail stores. This is as opposed to Hand loads which have been assembled by individuals and are not typically sold.

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.

Open Bolt

A type of firearm in which the action is in the open position and the chamber empty prior to firing. When the trigger is pressed the bolt moves forward, chambering a cartridge and firing it and returning to the open position. When firing is stopped the bolt remains open and the chamber empty.

Rim

The edge on the base of a cartridge case which stops the progress of the case into the chamber.

Cocked

A state of readiness of a firearm. The hammer (or similar mechanism if there is no hammer) only needs to be released by the trigger to cause the gun to fire.

Slide Catch

Sometimes also known as a slide lock, slide release or slide lever. On a semi-autmatic gun, the lever or catch that holds the slide open (after the last round is fired or when racking an empty gun). Typically they are located on the left side of the frame about mide barrel. Some of the newer semi-automatic pistols have an internal slide lock. Even though on pistols with an external slide catch, you can push down on the lever to release the slide, it should never be used in such a manner. The proper way to release the slide is to rack the slide.

Bolt Face

The forward end of the bolt which supports the base of the cartridge and contains the firing pin.

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