|Place of origin||United States|
|Used by||United States|
|Case type||Rimmed, bottleneck|
|Bullet diameter||.308 in (7.8 mm)|
|Land diameter||.301 in (7.6 mm)|
|Neck diameter||.338 in (8.6 mm)|
|Shoulder diameter||.423 in (10.7 mm)|
|Base diameter||.457 in (11.6 mm)|
|Rim diameter||.545 in (13.8 mm)|
|Rim thickness||.064 in (1.6 mm)|
|Case length||2.314 in (58.8 mm)|
|Overall length||3.089 in (78.5 mm)|
|Case capacity||58.0 gr H2O (3.76 cm3)|
|Maximum pressure (C.I.P.)||47,137 psi (325.00 MPa)|
|Maximum pressure (SAAMI)||N/A|
|Maximum CUP||40,000 CUP|
|Source(s): Hodgdon |
The .30-40 Krag (also known as .30 U.S. and .30 Army) was a cartridge developed in the early 1890s to provide the U.S. armed forces with a smokeless powder cartridge suited for use with modern small-bore repeating rifles to be selected in the 1892 small arm trials. Since the cartridge it was replacing was the .45-70 Government, the round was considered small-bore at the time. The design selected was ultimately the Krag–Jørgensen, formally adopted as the M1892 Springfield. It was also used in M1893 and later Gatling guns.
History and development
Though the U.S. Navy and Marine Corps had adopted limited numbers of smokeless powder and bolt-action rifles, the .30-40 was the first cartridge adopted by the US Army that was designed from the outset for smokeless powder. It was patterned after .303 British, to which it is very similar geometrically. After a brief experiment with a 230-grain bullet loading, the .30 Army loading was standardized in 1894 using a 220-grain (14 g) metal-jacketed round-nose bullet with 40 gr (2.6 g) of nitrocellulose powder. This loading developed a maximum velocity of 2,000 ft/s (610 m/s) in the 30-inch (760 mm) barrel of the Krag rifle, and 1,960 ft/s (600 m/s) in the 22-inch (560 mm) barrel of the Krag carbine.
The rimmed .30-40 round was also known as .30 Army or .30 U.S. Although the .30-40 Krag was the first smokeless powder round adopted by the U.S. military, it retained the "caliber-charge" naming system of earlier black powder cartridges, i.e. a .30-caliber bullet propelled by 40 grains (2.6 g) of smokeless powder. The first use of a smokeless powder round by Winchester was a single shot in 30–40, and it was one of only three rounds for which the 1895 Winchester lever action, introduced in 1896, was originally chambered.
From the outset, the .30-40 cartridge proved popular for hunting and was chambered in a variety of firearms. In 1899, a Krag in .30-40 caliber was used to shoot the world-record Rocky Mountain elk. The record stood until the latter half of the 20th century.
In October 1899, after reviewing the experiences of the Spanish–American War, U.S. Army ordnance authorities developed a new loading for the .30 Army used in the Krag rifle, in an attempt to match the ballistics of the 7×57mm Mauser cartridge employed by Spanish forces in that conflict. The new loading increased the muzzle velocity in the rifle version of the Krag to 2,200 ft/s (670 m/s) at 45,000 psi. However, once the new loading was issued, reports of cracked locking lugs on service Krags began to surface. In March 1900 the remaining stocks of this ammunition (some 3.5 million rounds) were returned to the arsenals, broken down, and reloaded back to the original 2,000 ft/s (610 m/s) specification.
In 1903, after recommendations from the infantry Small Arms Board, the U.S. Army formally adopted a higher-velocity .30-caliber replacement for the .30-40 or .30 Army cartridge. The new cartridge was designated by its year of adoption, the .30-03.
Rifles, handguns, and other weapons chambered in .30-40 Krag
- Winchester High-Wall
- M1885 Remington-Lee (Remington-Lee bolt-action)
- Remington Rolling Block
- Gatling gun, M1893 and later
- Winchester Model 1895
- Ruger No. 1
- Ruger No. 3
- Thompson-Center Encore
- List of rifle cartridges
- Table of handgun and rifle cartridges
- .30-03 (.30-45)
- .30-06 Springfield
- 7 mm caliber other cartridges of similar size.
- ".30-40 data at Hodgdon Online". Archived from the original on 2007-11-11. Retrieved 2007-08-01.
- "A Tale of Three .30s". 7 March 2019.
- Johnson, Melvin M. Jr. (1944). Rifles and Machine Guns. New York: William Morrow & Company. p. 384.
- History of Winchester Firearms, 1866–1992, Thomas Henshaw, p 44-45
- Barnes, Frank C; Skinner, Stan (Ed.) (1965, 1969, 1972, 1980, 1985, 1989, 1993, 1997, 2000, 2003). Cartridges of the World (10th ed.). Iola, Wisconsin: Krause Publications. ISBN 0-87349-605-1.
- .30-40 Krag by Chuck Hawks
- Hornady Handbook of Cartridge Reloading vol I, Sixth Edition; Book by Hornady Mfg Co, 2003
- Ordnance Department, United States (1917). Handbook of the Gatling Gun, Caliber .30. Washington, D.C.: Government Printing Office.
- Cartridge Dimensions at Steve's Pages