Grazing fire is a term used in military science and defined by NATO and the United States Department of Defense as "Fire approximately parallel to the ground where the center of the cone of fire does not rise above one meter from the ground." [1] Grazing fire is often performed by machine guns. It is tactically advantageous when attempting to cut off an infantry ground assault or counter-attack. [2]
In grazing fire, the cone of fire does not exceed 1.8 metres (5 ft 11 in)—the average height of a soldier—above the ground. When each bullet is fired, it will leave the barrel of the weapon at the axis of bore set from the angle of sight desired to strike the target area. The trajectory of the round should be constant as well as maximum ordinate. Maximum ordinate is the highest point of the trajectory, which is usually two-thirds the distance to the target from the weapon. Depending on the caliber of the round being fired and the slope of the terrain, as well as the distance to the target, the bullet will maintain a semi-flat trajectory. With 7.62×51mm NATO ammunition, which is most commonly used with, for example, the M240 machine gun, the bullet will reach a distance of 600 metres (2,000 ft) traveling at 900 metres per second (3,000 ft/s), before it begins a pronounced downward trajectory to the earth. Any distance beyond that range will be considered plunging fire due to the arc (axis of bore plus angle of sight) needed to impact the target area.
Grazing fire is so named because it cuts the vegetation low as though a herd of cattle had been grazing there. The optimal height of fire should be at knee height. In addition to keeping the enemy pinned down, anybody wounded or going to cover will fall into the line of fire, not out of it.
The 5.56×45mm NATO is a rimless bottlenecked intermediate cartridge family developed in the late 1970s in Belgium by FN Herstal. It consists of the SS109, L110, and SS111 cartridges. On 28 October 1980, under STANAG 4172, it was standardized as the second standard service rifle cartridge for NATO forces as well as many non-NATO countries. Though they are not entirely identical, the 5.56×45mm NATO cartridge family was derived from and is dimensionally similar to the .223 Remington cartridge designed by Remington Arms in the early 1960s.
In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the projectile longitudinally by conservation of angular momentum, improving its aerodynamic stability and accuracy over smoothbore designs.
A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found in warfare and sports.
Indirect fire is aiming and firing a projectile without relying on a direct line of sight between the gun and its target, as in the case of direct fire. Aiming is performed by calculating azimuth and inclination, and may include correcting aim by observing the fall of shot and calculating new angles.
The .50 Browning Machine Gun is a .50 in (12.7 mm) caliber cartridge developed for the M2 Browning heavy machine gun in the late 1910s, entering official service in 1921. Under STANAG 4383, it is a standard service cartridge for NATO forces as well as many non-NATO countries. The cartridge itself has been made in many variants: multiple generations of regular ball, tracer, armor-piercing (AP), incendiary, and saboted sub-caliber rounds. The rounds intended for machine guns are made into a continuous belt using metallic links.
Tracer ammunition (AMO) (Tracers) are bullets or cannon-caliber projectiles that are built with a small pyrotechnic charge in their base. When fired, the pyrotechnic composition is ignited by the burning powder and burns very brightly, making the projectile trajectory visible to the naked eye during daylight, and very bright during nighttime firing. This allows the shooter to visually trace the flight path of the projectile and thus make necessary ballistic corrections, without having to confirm projectile impacts and without even using the sights of the weapon. Tracer fire can also be used as a marking tool to signal other shooters to concentrate their fire on a particular target during battle.
External ballistics or exterior ballistics is the part of ballistics that deals with the behavior of a projectile in flight. The projectile may be powered or un-powered, guided or unguided, spin or fin stabilized, flying through an atmosphere or in the vacuum of space, but most certainly flying under the influence of a gravitational field.
A wadcutter is a special-purpose flat-fronted bullet specifically designed for shooting paper targets, usually at close range and at subsonic velocities typically under approximately 900 ft/s (274 m/s). Wadcutters have also found favor for use in self-defense guns, such as .38 caliber snubnosed revolvers, where, due to short barrel lengths, maximum bullet velocities are usually low, typically under 900 ft/s (274 m/s), and improved lethality is desired. Wadcutters are often used in handgun and airgun competitions.
In military science, suppressive fire is "fire that degrades the performance of an enemy force below the level needed to fulfill its mission". When used to protect exposed friendly troops advancing on the battlefield, it is commonly called covering fire. Suppression is usually only effective for the duration of the fire. It is one of three types of fire support, which is defined by NATO as "the application of fire, coordinated with the maneuver of forces, to destroy, neutralise or suppress the enemy".
Internal ballistics, a subfield of ballistics, is the study of the propulsion of a projectile.
The .308 Winchester is a smokeless powder rimless bottlenecked rifle cartridge widely used for hunting, target shooting, police, military, and personal protection applications globally. It is similar but not identical to the 7.62×51mm NATO cartridge.
Iron sights are a system of physical alignment markers used as a sighting device to assist the accurate aiming of ranged weapons, or less commonly as a primitive finder sight for optical telescopes. The earliest sighting device, it relies completely on the viewer's naked eye, and is distinctly different to optical sights such as telescopic sights, reflector (reflex) sights, holographic sights and laser sights, which make use of optical manipulation and/or active illumination, as well as the newer optoelectronics, which use digital imaging and even incorporate augmented reality.
Point-blank range is any distance over which a certain firearm can hit a target without the need to compensate for bullet drop, and can be adjusted over a wide range of distances by sighting in the firearm. If the bullet leaves the barrel parallel to the sight, the bullet, like any object in flight, is pulled downwards by gravity, so for distant targets, the shooter must point the firearm above the target to compensate. But if the target is close enough, bullet drop will be negligible so the shooter can aim the gun straight at the target. If the sights are set so that the barrel has a small upward tilt, the bullet starts by rising and later drops. This results in a weapon that hits too low for very close targets, too high for intermediate targets, too low for very far targets, and point blank at two distances in between. For a .270 Winchester, as an example, the bullet first crosses the line of sight at about 23 metres as it is rising and has a maximum impact above the line of sight of approximately 75 mm and crosses the line of sight again at about 250 metres. This is for a 130 grain hunting bullet. Therefore point blank range for a deer size target is about 275 metres . Point-blank range will vary by a weapon's external ballistics characteristics and the allowable error at the target; the flatter the bullet's trajectory or the larger the target, the longer the point-blank range will be.
A shooting range, firing range, gun range or shooting ground is a specialized facility, venue, or field designed specifically for firearm usage qualifications, training, practice, or competitions. Some shooting ranges are operated by military or law enforcement agencies, though the majority of ranges are privately owned by civilians and sporting clubs and cater mostly to recreational shooters. Each facility is typically overseen by one or more supervisory personnel, variously called a range master or range safety officer (RSO) in the United States, or a range conducting officer (RCO) in the United Kingdom. Supervisory personnel are responsible for ensuring that all weapon safety rules and relevant government regulations are followed at all times.
The .45-70 rifle cartridge, also known as the .45-70 Government, was developed at the U.S. Army's Springfield Armory for use in the Springfield Model 1873, which is known to collectors as the "Trapdoor Springfield." The new cartridge was a replacement for the stop-gap .50-70 Government cartridge, which had been adopted in 1866, one year after the end of the American Civil War.
Gun laying is the process of aiming an artillery piece or turret, such as a gun, howitzer, or mortar, on land, in air, or at sea, against surface or aerial targets. It may be laying for direct fire, where the gun is aimed similarly to a rifle, or indirect fire, where firing data is calculated and applied to the sights. The term includes automated aiming using, for example, radar-derived target data and computer-controlled guns.
The following are terms related to firearms and ammunition topics.
An underwater firearm is a firearm designed for use underwater. They are in the arms inventories of many nations. A common feature of underwater firearms or needleguns is that they fire flechettes or spear-like bolts instead of standard bullets. These may be fired by pressurised gas.
The bore axis of a firearm is the longitudinal axis through the geometric center of the gun barrel. In a rifled barrel, the projectile will spin around the bore axis as it goes through the barrel.
In ranged weapons such as firearms and artillery pieces, sighting in or sight-in is a preparatory or corrective calibration of the sights with the goal that the projectile may be placed at a predictable impact position within the sight picture. The principle of sighting-in is to shift the line of aim until it intersects the parabolic projectile trajectory at a designated point of reference, so when the gun is fired in the future it will repeatably hit where it aims at identical distances of that designated point.