Magazine - The container holding the ammunition in readiness for chambering in a repeating arm. Usually box-like ( either detachable or built into the receiver ) in which the cartridges are stacked vertically or spirally ( rotary magazine ), sometimes a tube in which they lie nose to tail. In all types, the first cartridge rests on or against a platform or magazine follower which progressively compresses a spring within the magazine as the rounds are loaded into it, the outermost one being held in place by the lips at the mouth. In return, the magazine spring forces the cartridges towards the mouth as each outermost one is scooped off and chambered by the bolt or breech block mechanism. Sometimes also used, wrongly, as alternative for Clip.
Magazine follower - The sliding plate or platform in a magazine, which supports the ammunition, riding atop the magazine spring.
Magnum - A term commonly used to describe a rimfire or centerfire cartridge, or shotshell, that is larger, contains more shot or produces higher velocity than standard cartridges or shells of a given calibre, or gauge. Rifles, handguns or shotguns that are designed to fire magnum cartridges or shells may also be described with the term Magnum. (abbr. Mag).
Magnus effect - A moving, rotating bullet in the air, drags some of the air around with it, in its direction of rotation. This increases the speed in that region, and thus the pressure is lower. Consequently, there is a net force on the bullet in the direction of spin, perpendicular to the forward movement of the bullet. This is called the Magnus effect.
Mannlicher - 19th century Austrian designer/manufacturer who gave his name to a rotary magazine bolt action rifle and cartridges ( 6,5mm & 9,5mm Mannlicher ). Firm since taken over by Steyr who market Steyr-Mannlicher rifles. His name has become synonymous with full-length stocks ( fore-end extended to the muzzle ) which characterised his rifles.
Manually operated safety - A mechanism which prevents a firearm from firing. There are different types, of which some are: Cross bolt: a type of firearm safety operated by lateral force on a button usually located in the trigger guard. Grip: an auxiliary locking device in the grip of some handguns which prevents firing until it is depressed. (example: US 1911 pistol). Half cock: a sear engagement which holds the hammer back away from the firing pin. Hammer block: a device intended to separate the hammer from the firing pin except when the trigger is pulled. Lever: a type of firearm safety operated by the movement of a pivoted lever. (example: Luger pistol). Sliding button: a safety mechanism on a firearm that is operated by a sliding motion. Tang: a safety mounted on the upper receiver tang of a firearm. Thumb: a safety on a firearm so located as to be operated conveniently by the thumb of the trigger hand. Wing: a safety found on bolt action rifles, usually mounted at the rear of the bolt assembly, and pivots up and down at right angles to the bore line in the manner of a bird's wing.
Match / Match grade - Term to describe ammunition or bullets made with special care for superior accuracy, intended for competitive target shooting. Commercial match-grade jacketed rifle bullets are extremely fragile and should never be used for game hunting.
Match rifle - Specifically designed for target shooting.
Mauser - Famous 19th century German firearm designer of bolt action rifles, semi-auto pistols and several cartridges. Most "standard calibre" rifle cartridges ( i.e. .270, .308, .30-06, etc. ) are based on Mausers original 7X57 and 8X57 case head dimensions. Mauser founded the firm Waffenfabrik Mauser Oberndorf ( later known as Mauser Werke, Oberndorf ) which became Germanys major military arsenal until their defeat in WWII, after which the factories were closed. The company later reopened and today makes sporting rifles.
Mauser action - Usually the famous Model 98 bolt action, widely regarded as the best ever designed, certainly the most widely copied. Originally for military use, identical versions were made by European arsenals under German command, such as DWM, FN, BRNO, etc. Mauser M98 military rifles, commonly ( but inaccurately ) known as "Kk98s", have become commercially available in large numbers, hence the actions are popular for building sporters. Mauser also made a more refined commercial version prior to WWII, now keenly sought by collectors and custom gunsmiths. The term "Mauser action" is sometimes applied to any action with M98 design features, such as cock-on-opening, controlled feeding ( non-rotating claw extractor ) etc.
Mean Radius - The average radius of shot dispersion from the center of a shot group.
Meplat - The truncated flat area on the leading end of certain projectiles.
Mercuric primers - Primers, usually Berdan type, that have priming compounds containing fulminate of mercury. The trouble with Mercury Fulminate primers is that elemental mercury is released on ignition, and amalgamates with the Copper in the brass, causing it to become brittle. This cannot be prevented, neither can the process be reversed. In the Age of Blackpowder, this was not a problem, as the fouling of the BP absorbed the mercury before it could get into the case metal. It became a problem with the higher pressure smokeless loadings. Also see Corrosive primers.
Mid range trajectory - In its curved path, the highest vertical distance reached by a bullet above the line of sight. The term is a misnomer as the highest point in a bullets trajectory does not occur at "mid-range" but slightly beyond ( due to the bullets progressive slowing, the curve is in the form of a parabola, not a perfect arc ). MRT figures also apply to given loads and also depend on the height of the scope ( or sights ) above the bore. Useful for determining how low one needs to aim when a small target is closer than the zero range of the scope. See Line of sight, Trajectory. ( Click here for picture. )
Mil - An angular unit of measurement equal to 1/6400 of a complete revolution (there are 6400 mils in 360 degrees). The mil is used to estimate distance and size based on the mil relation formula: 1 mil equals 1 meter at 1,000 meters. There are 3.375 MOA in 1 mil.
Minute of Angle ( MOA ) - Angular unit of measure used to describe the accuracy potential of rifles, ammunition, bullets or loads. One MOA equals 1/60th of a degree ( 21 600 minutes in a circle ) and subtends 1.047 inches at 100 yards, or, for practical purposes, 1" at 100 yards. In hunting terms, a rifle/load which, at 100 yards, can consistently place five consecutive shots in a cluster measuring 1" between the centres of the two outermost holes ( "minute of angle groups" ) is considered extremely accurate. For Benchrest competitions the figure is obviously much less. See Group.
Mirage - The heat waves or the reflection of light through layers of air of different densities and temperatures. With optical aids, mirage can be seen even on the coldest days. Mirage is used to estimate the effective wind to be applied to the sight of the SWS.
Misfire - A failure of the priming mixture to be initiated after the primer has been struck by a firing-pin or the failure of the initiated primer to ignite the powder.
Modern - A legal term applied to cartridge firearms manufactured after 1895.
Momentum - The product of a bullet's weight in pounds multiplied by its velocity. Commonly expressed as pounds/feet (lbs/ft); i.e., 9mmP 115gr bullet at 1175fps. (115 / 7000) * 1175 = 19.3 lbs/ft.
Monolithic bullets - A bullet that is formed from one single piece of material. It is normally lathe-turned, and made from a copper alloy. Because copper is a lighter material than lead, monolithic bullets of the same weight and calibre are normally longer than their leaded counterparts, which might cause problems in some rifle, both as far as length and barrel twist is concerned. Normally a monolithic bullet will have better weight retention in a target than a lead-core bullet, which can shed its core. For hunting purposes this means that a lighter bullet can be used, with the same effects. Also called monometal bullets. Also see Full-metal jacket, Solid-nose bullet.
Monte Carlo - A stock with a raised comb to bring the eye in alignment with the sight.
Mouth - The opening at the neck end of a cartridge case, via which the bullet is seated. ( Click here for picture. )
Mushroom - Verb: The expansion process of a bullet as it penetrates a target, during which the front end enlarges in diameter ( in the shape of a mushroom on its side ). Purpose is to cause maximum tissue destruction for rapid death or incapacitation, by creating a larger wound channel than the calibre of the bullet. Noun: A recovered bullet which has successfully expanded. See Controlled Expansion.
Musket - Military firearm with long barrel and fore-end or forearm extending nearly to muzzle.
Muzzle - The end of a gun barrel from which the bullet or shot emerges.
Muzzle brake - Device at the muzzle end usually integral with the barrel that uses the emerging gas behind a projectile to reduce recoil. See Compensator.
Muzzle energy ( ME ) - Kinetic energy or force carried by a bullet as it exits the muzzle of a firearm. See Energy.
Muzzle Velocity - The speed of a projectile as it leaves the muzzle of the weapon. ( Industry standard for measuring is 15" from muzzle.)
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