Springfield Model 1873

The Model 1873 "Trapdoor" Springfield was the first standard-issue breech-loading rifle adopted by the United States Army (although the Model 1866 trapdoor had seen limited issue to troops along the Bozeman Trail in 1867). The gun, in both full-length and carbine versions, was widely used in subsequent battles against the American Indians.

The Model 1873 was the fifth variation of the Allin trapdoor design, and was named for its hinged breechblock, which opened like a trapdoor. The infantry rifle model featured a 32 $5/8$ -inch (829 mm) barrel, while the cavalry carbine used a 22 in barrel. It was superseded by an improved model, the Springfield Model 1884, also in .45-70 caliber.

Selection process
In 1872–1873 a military board, headed by Brigadier-General Alfred H. Terry, conducted an examination and trial of 99 rifles from several domestic and foreign manufacturers including those from Springfield, Sharps, Peabody, Whitney, Spencer, Remington, and Winchester pursuant to the selection of a breech loading system for rifles and carbines for the U.S. Military. The trials included tests for: accuracy, dependability, rate-of-fire, and ability to withstand adverse conditions. Both single shot and magazine equipped systems were considered but, at the time, the single shot was deemed to be more reliable. Firing tests were held at the Springfield Armory and Governor's Island where the average rate of fire for the Springfield was 8 rounds per minute for new recruits and 15 rounds per minute for experienced soldiers. The board recommended "No. 99 Springfield" which became the Model 1873.

Ballistics
The rifle cartridge was designated as ".45-70-405", indicating a .45 caliber, 405 gr bullet propelled by 70 gr of black powder. It had a muzzle velocity of 1350 ft/s, making it a powerful and effective load for the skirmish tactics of the era. A reduced-power load of 55 gr of powder (Carbine Load) was manufactured for use in the carbine to lighten recoil for mounted cavalry soldiers. This cartridge had a correspondingly reduced muzzle velocity of 1100 ft/s and a somewhat reduced effective range.

Use in combat
The rifle was originally issued with a copper cartridge and used in the American West during the second half of the 19th century, but the soldiers soon discovered that the copper expanded excessively in the breech upon firing. This sometimes jammed the rifle by preventing extraction of the fired cartridge case. A jam required manual extraction with a knife blade or similar tool, and could render the carbine version of the weapon, which had no ramrod to remove stuck cases, useless in combat except as a club.

After the annihilation of Lieutenant-Colonel George Armstrong Custer's battalion (armed with the carbine and carbine load ammunition) at the Battle of the Little Bighorn in June 1876, investigations first suggested that jamming of their carbines may have played a factor, although archaeological excavations in 1983 discovered evidence that only 3.4 percent of the cases recovered showed any indication of being pried from jammed weapons. This did not account for cases removed by a ramrod or other "stick" nor for jammed rifles cleared away from the immediate battle area and outside the very limited archaeological survey area. Every Custer battalion weapon became Indian property. Captain Thomas French, M Company Commander was kept busy on the Reno defensive position line using the ramrod from his infantry rifle to clear the jammed carbines passed to him from the rifleman on the line. The cartridge was subsequently redesigned with a brass case, since that material did not expand as much as copper. This was shown to be a major improvement, and brass became the primary material used in United States military cartridges from then to the present. After the Little Big Horn disaster, troops were required to perform target practice twice a week. The black powder Model 1873 continued to be the main service rifle of the U.S. Military until it was gradually replaced by the Krag-Jørgensen bolt-action rifle (using smokeless powder) starting in 1892. It still was used by secondary units during the Spanish–American War in Cuba and the Philippines, although it was at a major disadvantage against the Spanish forces armed with 7 mm Spanish M93 Mauser bolt-action rifles using smokeless powder.