.45-70

The .45-70 was adopted by the United States Army in 1873, with the Springfield Model 1873 built around it, to replace the stop-gap .50-70 taken up seven years earlier. It is a straight, rimmed, black-powder case that has outlived every rifle it was designed for, and it survives because its geometry suits a class of arm — the single-shot breechloader and the lever gun — that nothing since has replaced.

Nothing about the case is subtle. It is 53.47 mm long and tapers only 0.65 mm from a base of 12.84 mm to a neck of 12.19 mm, so there is no shoulder to headspace on and the job falls to a rim standing 2.6 mm proud of the base. That rim is why the round still works in falling-block and lever actions: extraction depends on a positive flange rather than on a groove, and a rimmed case will feed from a tubular magazine that has no way to control a rimless one. The bullet is 11.63 mm across and blunt, because a tubular magazine stacks primer against bullet nose and a pointed one is not welcome there.

Two service loads are recorded here, both from Springfield Armory’s own test data: a 405-grain rifle round published in 1874 and a heavier 500-grain round published in 1887, the first at about 411 m/s and the second at about 401 m/s from the rifle’s 32.6-inch barrel. A third, deliberately reduced, carbine round existed for the shorter Springfield carbine. The Army’s own tests put the 1873 rifle at 19,000 psi and the Model 1884 firing the heavier bullet at 25,000 psi — figures that explain why modern loading data for this cartridge is published in three separate pressure tiers according to what action the round is going into.

The .45-70 left front-line service in 1893 when the Army adopted the .30-40 Krag, lingered with the National Guard, Navy and Marine Corps until 1897, and was last used in quantity in 1898. It remains a US military item in one form: the caliber .45 M32 line-throwing blank.

Gaps on this page: the two loads are the encyclopedia’s ballistics table, which attributes them to Springfield Armory publications of 1874 and 1887 — books, not clickable documents — and states one 32.6-inch test barrel for the table as a whole; the carbine round is not recorded because no barrel length is published beside it, and the modern high-pressure handloading rows in the same table are not recorded because they are loading-manual data rather than a factory measurement. No ballistic coefficient is given for either bullet. The C.I.P. dimensions transcribed here are the modern commercial maxima and are not necessarily the 1873 arsenal drawing.