.30-40 Krag

The .30-40 Krag, originally designated the .30 U.S. or .30 Army, is a rimmed, bottlenecked rifle cartridge adopted by the United States in 1892 for the Krag–Jørgensen rifle. It was the first smokeless-powder cartridge issued by the US military, replacing the black-powder .45-70 Government and its trapdoor Springfield, and it saw combat in the Spanish–American War before the US Army replaced both rifle and cartridge with the M1903 Springfield and the rimless .30-03 in the early 1900s.

Its name follows the black-powder-era convention of pairing bore diameter with a second number — here 40, for the original 40-grain smokeless charge, not a black-powder weight — a naming quirk this site records as a fact about how the cartridge got its name rather than as a stated load. At a 325 MPa C.I.P. pressure ceiling and a rimmed, single-locking-lug action behind it, the Krag rifle could not be loaded as fast from a magazine as its rimless European contemporaries, one of the technical shortcomings that pushed the US Army toward the rimless Mauser-influenced M1903 within a decade.

This entry carries the full C.I.P. dimensional standard and one current factory load, Hornady’s Custom 180-grain spire point rated at 740.8 m/s from a stated 24-inch test barrel — this reflects a modern sporting-rifle loading, not the original 1892 military charge. No ballistic coefficient is published on that product page, so the cartridge computes a muzzle energy figure but no trajectory.