This guide provides sources on the development of military shoulder arms (rifles and shotguns) which began to be adopted by armies in the mid-1800s.These weapons needed to be reliable, durable, and capable of being mass-produced. They had be accurate at great distances, needed to fire rounds with sufficient stopping power, supply rapid fire when needed and be easily reloaded. Early examples in development during the use of muzzle-loading muskets resulted in semi-reliable guns consisting of single shot breech loaders that could be reloaded somewhat rapidly under ideal conditions. They often met with considerable problems when used in the unpredictable conditions of combat.

An illustrative example in which a breech-loading rifle's capabilities may have contributed to a disastrous military defeat was the United States 7th Cavalry Regiment's defeat at the Battle of the Little Bighorn in June, 1876. In combination with Lt. Col. George Armstrong Custer's decision to divide his cavalry force into three columns, troopers' 1873 Springfield carbines were thought to have suffered breech jams during combat. This forced troopers and officers to spend time prying out the carbines' spent copper shell casings that could expand in the heated breech chamber and become wedged in the carbines' breech. Also, copper used in the shell casings may have chemically reacted to the leather cartridge belts and resulted in a thin layer of corrosion which may have made the shell casings difficult to extract. This reduced the volume of fire from an already out-numbered force and likely contributed to a breakdown of the troopers' defensive lines, and resulted in the total annihilation of officers, troopers, hired scouts and several civilians in the column led by Col. Custer. This defeat led to investigations and modifications that included changing the copper shell casing to brass.

Breech loading designs similar to the 1873 Springfield were used by other nations and competed with other loading systems. The British Martini-Henry used a ventral lever behind the trigger to open and close the breech block during loading and extraction of cartridges. Other systems included the outdated revolving cylinder seen in the Colt Revolving rifle, an inserted tube magazine used in the Spencer Rifle, the affixed tube magazine of lever-operated, repeating arms including the Henry Rifle and the Winchester Rifle, and bolt-action rifles that began with single shot examples.

The development of early bolt-action rifles began with European inventors in Norway (the Kammerlader), France (the Chassepot) and Germany (Dreyse Needle Gun). The Kammerlader was particularly early in its 1840s development and adoption by the Norwegian Army and Navy. The Chassepot and the Dreyse Needle Gun saw extensive use in the Franco-Prussian War (1870-1871). These early bolt-action rifles were essentially breech loaders with different breech mechanisms. More advanced designs replaced needle guns such as the 1871 Mauser Gewehr 71, and the 1874 French Gras Rifle. Both used brass cartridges whereas the needle guns had used paper and linen cartridges. The Gewehr 71 was later updated to a repeating rifle with the addition of a tube magazine.

Ultimately, the system universally adopted was the bolt-action, magazine-fed rifle using a stripper clip or charger clip to load rounds by mounting the removable rim railed clip in a notch on top of the rifle, pushing the rounds down into an affixed box magazine and removing the empty rim railed clip, or by attaching a pre-loaded box magazine. World War I (1914-1918) was a conflict not seen before, both in scale and in numbers of casualties suffered. Though a great percentage of these casualties are attributed to artillery and machine guns, massed troops armed with modern, bolt-action magazine rifles were vital in holding defensive lines and making up the force of an offensive's attack. Machine guns both light and heavy, and automatic rifles anchored defensive lines and supplemented the firepower of troops on the attack.

Bolt-action magazine rifles remained in front-line service with most nations from the 1880s through the 1960s and many are still in service today in military reserve forces, militias, police forces and non-state armed groups. Bolt-action rifles were used in the millions by nations seeking to enrich themselves by acquiring colonies and exclusive trade zones in other countries. As late as 2013, examples of the 1874 Gras Rifle were still available for street sale in Yemen. Bolt-action rifles were used in regional conflicts between neighboring countries. They were used in civil wars, internal waves of violence against targeted groups, coup de etats, revolutions, wars of alliances and world wars. Many millions of bolt-action rifles caused the injuring and killing of countless numbers of soldiers and civilians. The Boer Wars, Brazilian War of the Canudos, the Spanish American War, the Colombian Thousand Days War, the Boxer Rebellion, the Russo-Japanese War, the Philippine American War, the Balkan Wars, the Mexican Revolution, the Chaco War, World War I, the Russian Revolution, the Russian Civil War, the Polish-Soviet War, the Chinese Revolution, the Sino-Japanese War, the Italo-Ethiopian Wars, the Spanish Civil War, World War II, the Soviet-Finn Winter War, the Franco-Thai War, the Ecuadorian-Peruvian War, the Greek Civil War, the Chinese Civil War, the 1948 Arab-Israeli War, the Korean War, the French Indochina War, the 1956 Arab-Israeli War and Suez Crisis, the Vietnam War, the 1967 Arab-Israeli Six-Day War, the 1973 Yom Kippur War, and so many others saw use and re-use of bolt-action rifles.

Hoping to provide greater volumes of fire and put that in the hands of each soldier, weapon developers began experimenting with semi-automatic rifle designs. Semi-automatic rifles did not see extensive use in WWI as they had not been perfected by the war's end in 1918. These weapons would see widespread use in the next global war, World War II (1939-1945). Arguably the best known example of semi-automatic rifles was the M-1 Garand. Developed in the 1920s by John Garand (1888-1974), and accepted in 1936 to replace the 1903 Springfield Rifle, the Garand held an 8-round en bloc clip loaded by pushing a full clip into the open receiver. When the bolt closed, the first round would load into the chamber. Firing the last round produced a distinctive "ping" as the now empty clip was ejected from the open receiver. General George S. Patton (1885-1945) referred to the Garand as "the best battle implement ever devised." The M-1 remained in front-line service well into the 1950s, and in the National Guard for several more decades, as well as in the armies of many other nations. The M-1 Garand maintains a solid reputation and examples are highly sought after by private collectors. Modernizing the Garand resulted in the M-14 Rifle, which was adopted by the US military beginning in the late 1950s. It was the last battle rifle adopted by the US military. In 1967, the M-14 was replaced by the M-16 Rifle which was capable of semi and full automatic fire. Other nations also developed semi-automatic rifles during WWII, but none were as successful or widespread as the Garand. The Soviet rifles SVT-38, SVT-40, and the SKS, and the German rifles G-41 and G-43 are examples of these weapons.