Letter H

The Definition of Hornady Magnum Rimfire

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Hornady Magnum Rimfire

A type rimfire rifle cartridge developed by the ammunition company Hornady. .17 Hornady Magnum Rimfire (4.527mmR), commonly known as the .17 HMR, was developed in 2002. It descended from the .22 Magnum by necking down the .22 Magnum case to take a .17 caliber (4.5 mm) bullet.


19 Other Firearms Definitions You Need To Know


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.

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.

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.

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.

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.

Hardball

Slang for a full metal jacket bullet with a round nose. The term is most commonly used in referring to .45 ACP caliber ammunition, but may be used for other calibers as well.

Battery

Most firearms do not have literal batteries. But a firearm is said to be in battery when the breech is fully closed and locked, ready to fire. When the breech is open or unlocked, the gun is out of battery and no attempt should be made to fire it. A semi-automatic is out of battery when the slide fails to come all the way forward again after the gun has fired, making it dangerous or impossible to fire the next round. This condition can be created by a misfeed, a dirty gun, weak springs, the shooter's thumbs brushing against the slide, riding the slide, or any of several other causes.

WC

Abbreviation for wadcutter.

Passive Safety

Any safety, internal or external, which functions apart from the shooter's conscious control. Grip safeties are one example of a passive external safety.

Chain Gun

A type of machine gun or autocannon that uses an external source of power to cycle the firearm.

Bedding

That part of the stock on a rifle or shotgun into which the barrel fits.

Hang Fire

An unexpected delay between the triggering of a firearm and the ignition of the propellant. This failure was common in firearm actions that relied on open primer pans, due to the poor or inconsistent quality of the powder. Modern weapons are susceptible, particularly if the ammunition has been stored in an environment outside of the design specifications. Reloaded ammunition may also be the cause if not reloaded properly

Ear Plugs

Hearing protection that fits inside the ear canal.

Kick

Slang for Recoil.

Pair

Two shots fired very quickly with the use of the sights.

Ejector Star

On a revolver, the collective ejector, manually operated through the center of an opened cylinder, when activated, clears all chambers at once.

Doughnut Pattern

A shotgun pattern with a hole in the middle generally caused by the interference of the top wad.

Drift

The departure of a bullet or shot charge from the normal line of flight. This can be caused by wind or the unbalanced spinning of the bullet.

Receiver

The housing for a firearm's breech (portion of the barrel with chamber into which a cartridge or projectile is loaded) and firing mechanism. In semi-automatic handguns and revolvers, this part is typically called the frame.