The bore axis of a firearm is the longitudinal axis through the geometric center of the gun barrel. In a rifled barrel, the projectile (bullet/ball, pellet or slug) will spin around the bore axis as it goes through the barrel.
Boresighting is a process of placing one's line of sight down along the bore axis.
The distance between the bore axis and the sight axis (the optical axis of a sighting device), also known as the sight height, is an important factor to consider due to parallax principles. It is normally desirable to keep the sights of a firearm as close to the bore as possible, since a firearm with a large bore-to-sight distance will require more compensatory sight adjustment when shifting between shooting at different targets at close ranges (due to foreshortening). On the other hand, a firearm with a short bore-to-sight distance will need less sight adjustment when changing between targets at close ranges. At longer ranges the bore-to-sight distance will be of less importance, since gravity has affected the projectile so much that the height difference between the bore axis and the sight axis has far less impact compared to the bullet drop.
Traditional bolt hunting rifles usually have had the optical center of about 38 mm (1.5 in) above the bore, while AR-type rifles and modern bolt-action rifles usually have their optical center about 68 mm (2.7 in) above the bore. [1]
On firearms with a picatinny rail, the distance from the bore to the optical axis can be divided into distance from bore axis to top of rail, and distance from top of rail to center of the optical axis. For example on an AR-type rifle, the mil-spec distance from center of bore to top of rail is 1.211 inches, or approximately 31 mm (1.2 in). The mount height itself, that is the distance from the top of rail to center of scope, varies, but typically lies around 36–38 mm (1.4–1.5 in) (higher and lower mounts are also readily available). In total, this gives a typical scoped AR-style rifle a height over bore of around 67–69 mm (2.6–2.7 in).
The recoil from a fired cartridge (and the action movement) exerts a rearward impulse along the bore axis, which is commonly above the center of mass of the gun. Meanwhile, the gripped areas of the gun, where the user will exert a reactional forward push countering the recoil, is almost always below the gun's center of mass. This force couple creates a rotational torque around the mass center and make the gun pitch upwards after each shot — a phenomenon known as muzzle rise . This is more prominent in shorter-barreled weapons such as handguns due to less frontal weight available to counter the upward lifting of the muzzle, and how high the bore axis sits above the gripping hand will also affect the degree of muzzle rise. A lower bore axis will align more of the recoil directly into the hand, creating less couple torque and thus less muzzle rise. Among other things that affect muzzle rise and felt recoil is the weight of the pistol frame and tuning of recoil springs. The presence of a buttstock in a long gun will also help negate the effect of muzzle rise by shifting the pivot of the muzzle rise back towards the butt end, thus utilizing the entire gun's weight with a longer lever to counter the rise.
Handguns lack a buttstock to aid in recoil control, so design elements that reduce felt recoil or muzzle flip are considered highly desirable and numerous manufacturers claim their handgun design has a low bore axis, although few offer measurements to prove this claim. While a lower bore axis does typically yield reduced felt recoil and muzzle flip, shooters intent on reducing these features as much as possible (such as competitive sport shooters) will typically seek out handguns with heavy steel frames, as increasing the weight of the gun's non-reciprocating mass (the frame) yields greater reductions in felt recoil and muzzle flip than any difference in bore axis height can typically achieve. [2] Handguns such as the CZ-75, which combine a heavy steel frame with a low bore axis (relative to other hammer-fired guns) achieve twofold reductions to felt recoil and muzzle flip, and are popular choices in many competitive shooting disciplines.
Striker-fired handgun designs are typically able to achieve a lower bore axis than their hammer-fired counterparts since strikers travel straight forward, rather than up and forward like a typical hammer mechanism.
One pistol which combines a low bore axis, striker fire and weight is the Wildebeest pistol.
A carbine is a long gun that has a barrel shortened from its original length. Most modern carbines are rifles that are compact versions of a longer rifle or are rifles chambered for less powerful cartridges.
A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and operated by an individual. The term is legally defined further in different countries.
The AK-74 is an assault rifle designed by small arms designer Mikhail Kalashnikov in 1974 as a successor to the AKM. While primarily associated with the Soviet Union, it has been used by many countries since the 1970s. It is chambered for the 5.45×39mm cartridge, which replaced the 7.62×39mm cartridge of Kalashnikov's earlier automatic weapons for the Soviet Armed Forces.
A muzzle brake or recoil compensator is a device connected to, or a feature integral to the construction of, the muzzle or barrel of a firearm or cannon that is intended to redirect a portion of propellant gases to counter recoil and unwanted muzzle rise. Barrels with an integral muzzle brake are often said to be ported.
Recoil is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, as according to Newton's third law the force required to accelerate something will evoke an equal but opposite reactional force, which means the forward momentum gained by the projectile and exhaust gases (ejectae) will be mathematically balanced out by an equal and opposite momentum exerted back upon the gun.
Internal ballistics, a subfield of ballistics, is the study of the propulsion of a projectile.
Iron sights are a system of physical alignment markers used as a sighting device to assist the accurate aiming of ranged weapons such as firearms, airguns, crossbows, and bows, or less commonly as a primitive finder sight for optical telescopes. Iron sights, which are typically made of metal, are the earliest and simplest type of sighting device. Since iron sights neither magnify nor illuminate the target, they rely completely on the viewer's naked eye and the available light by which the target is visible. In this respect, iron sights are distinctly different from optical sight designs that employ optical manipulation or active illumination, such as telescopic sights, reflector (reflex) sights, holographic sights, and laser sights.
Point-blank range is any distance over which a certain firearm or gun can hit a target without the need to elevate the barrel to compensate for bullet drop, i.e. the gun can be pointed horizontally at the target. For targets beyond-blank range, the shooter will have to point the barrel of their firearm at a position above the target, and firearms that are designed for long range firefights usually have adjustable sights to help the shooter hit targets beyond point-blank range. The maximum point-blank range of a firearm will depend on a variety of factors such as muzzle velocity and the size of the target.
Accurizing is the process of improving the accuracy and precision of a gun.
Metallic silhouette shooting is a group of target shooting disciplines that involves shooting at steel targets representing game animals at varying distances, seeking to knock the metal target over. Metallic silhouette is shot with large bore rifles fired freehand without support out to 500 meters, and with large bore handguns from the prone position with only body support out to 200 meters. Competitions are also held with airguns and black-powder firearms. A related genre is shot with bow and arrow, the metal targets being replaced with cardboard or foam. The targets used are rams, turkeys, pigs, and chickens, which are cut to different scales and set at certain distances from the shooter depending on the specific discipline.
The International Practical Shooting Confederation (IPSC) is the world's largest shooting sport association, and the largest and oldest within practical shooting. Founded in 1976, the IPSC nowadays affiliates over 100 regions from Africa, Americas, Asia, Europe, the Middle East, and Oceania. Competitions are held with pistols, revolvers, rifles, and shotguns, and the competitors are divided into different divisions based on firearm and equipment features. While everyone in a division competes in the Overall category, there are also separate awards for the categories Lady, Super Junior, Junior, Senior, and Super Senior.
Boresighting is a method of visually pre-aligning a firearm barrel's bore axis with the target, in order to more easily zero the gunsight. The process is usually performed on a rifle, and can be accomplished either with the naked eye, or with a specialized device called a boresighter.
A gunstock or often simply stock, the back portion of which is also known as a shoulder stock, a buttstock, or simply a butt, is a part of a long gun that provides structural support, to which the barrel, action, and firing mechanism are attached. The stock also provides a means for the shooter to firmly brace the gun and easily aim with stability by being held against the user's shoulder when shooting the gun, and helps to counter muzzle rise by transmitting recoil straight into the shooter's body.
The .30-30 Winchester / 7.8x51mmR cartridge was first marketed for the Winchester Model 1894 lever-action rifle in 1895. The .30-30, as it is most commonly known, along with the .25-35 Winchester, was offered that year as the United States' first small-bore sporting rifle cartridges designed for smokeless powder. Since its introduction, it has been utilized alongside the development of flatter shooting cartridges, most prominently those derived from designs subsidized by interest in military expenditures. The .30-30 has remained in widespread use almost entirely because of reliable effectiveness in civilian applications, and has put food on the table for millions of people in hunting situations.
The ArmaLite AR-7 Explorer is a semi-automatic firearm in .22 Long Rifle caliber, developed in 1959 from the AR-5 that was adopted by the U.S. Air Force as a pilot and aircrew survival weapon. The AR-7 was adopted and modified by the Israeli Air Force as an aircrew survival weapon in the 1980s.
Short-barreled rifle broadly refers to any rifle with an unusually short barrel. The term carbine describes a production rifle with a reduced barrel length for easier handling in confined spaces. Concern about concealment for illegal purposes has encouraged regulations specifying minimum barrel lengths and overall lengths.
The following are terms related to firearms and ammunition topics.
The Walther LGR air rifle was developed by the German arms manufacturer Carl Walther GmbH Sportwaffen as a high end match rifle for 10 metre air rifle competition shooting. The LGR was the first match air rifle that employed the then futuristic single-stroke pneumatic method as power source. This use of pre compressed air introduced the advantages of recoilless and vibration free shooting in combination with a well-made air rifle into the sport. It took other manufacturers a decade before they also introduced single-stroke pneumatic match air rifles.
Muzzle rise, muzzle flip or muzzle climb refers to the tendency of a firearm's or airgun's muzzle to rise up after firing. It more specifically refers to the seemingly unpredictable "jump" of the firearm's muzzle, caused by combined recoil from multiple shots being fired in quick succession. It has an adverse effect on maintaining accuracy with using automatic weapons or rapid-firing semi-automatic firearms, as a moving muzzle can throw off the shooter's aim, causing subsequent shots to miss the intended target.
A dovetail rail or dovetail mount can refer to several types of sliding rail system found on firearms, primarily for mounting telescopic sights. Colloquially, the term dovetail rail usually refer to any straight mounting bracket with an inverted trapezoid (dovetail) cross-section running parallel to the bore for mounting a scope or diopter sight to a rifle. These are sometimes also called "tip-off" mounts, and allow the user to easily take on or off the sight. Dovetail mount can also refer to a dovetail track running perpendicular to the bore.