.45-70

.45-70 Government
From left, .30-06, .45-70, and .50-90 Sharps
Type	Rifle
Place of origin	United States
Service history
Used by	United States
Wars	Spanish–American War
Production history
Designer	US Government
Designed	1873
Specifications
Case type	Rimmed, tapered
Bullet diameter	.458 in (11.6 mm)
Neck diameter	.480 in (12.2 mm)
Base diameter	.505 in (12.8 mm)
Rim diameter	.608 in (15.4 mm)
Rim thickness	.070 in (1.8 mm)
Case length	2.105 in (53.5 mm)
Overall length	2.550 in (64.8 mm)
Rifling twist	1-20"
Primer type	Large rifle
Ballistic performance
Bullet mass/type Velocity Energy 300 (Trapdoor) Lead PB 1,597 ft/s (487 m/s) 1,699 ft·lbf (2,304 J) 405 (Trapdoor) Lead FN 1,394 ft/s (425 m/s) 1,748 ft·lbf (2,370 J) 300 (Standard) JHP 2,069 ft/s (631 m/s) 2,852 ft·lbf (3,867 J) 300 (Strong) JHP 2,275 ft/s (693 m/s) 3,449 ft·lbf (4,676 J)
Test barrel length: 24" Source(s): Accurate Powder

The .45-70 rifle cartridge, also known as . 45-70 Government, was developed at the U.S. Army's Springfield Armory for use in the Springfield Model 1873, which is known to collectors as the "trapdoor Springfield". The new cartridge was a replacement for the stop-gap .50-70 Government cartridge which had been adopted in 1866, one year after the end of the American Civil War.

The new cartridge was completely identified as the .45-70-405, but was also referred to as the ".45 Government" cartridge in commercial catalogs. The nomenclature of the time was based on three properties of the cartridge:

The minimum acceptable accuracy of the .45-70 from the 1873 Springfield was approximately 4 inches (100 mm) at 100 yards (91 m), however, the heavy, slow-moving bullet had a "rainbow" trajectory, the bullet dropping multiple yards (meters) at ranges greater than a few hundred yards (meters). A skilled shooter, firing at known range, could consistently hit targets that were 6 × 6 feet (1.8 m) at 600 yards (550 m)—the army's standard target. It was a skill valuable mainly in mass or volley fire, since accurate aimed fire on a man-sized target was effective only to about 300 yards (270 m).

After the Sandy Hook tests of 1879, a new variation of the .45-70 cartridge was produced: the .45-70-500, which fired a heavier, 500 grain, (32.5 g) bullet. The heavier bullet produced significantly superior ballistics, and could reach ranges of 3,350 yards (3,120 m), which were beyond the maximum range of the .45-70-405. While the effective range of the .45-70 on individual targets was limited to about 1,000 yards (915 m) with either load, the heavier bullet would produce lethal injuries at 3,500 yards (3,200 m). At those ranges, the bullets struck point-first at a roughly 30 degree angle, penetrating three 1-inch (2.5 cm) thick oak boards, and then traveling to a depth of 8 inches (20 cm) into the sand of the Sandy Hook beach. It was hoped the longer range of the .45-70-500 would allow effective volley fire at ranges beyond those normally expected of infantry fire.

While the nominal bore diameter was .450 inches (11.4 mm), the groove diameter was actually closer to .458 inches (11.6 mm). As was standard practice with many early U.S. commercially produced cartridges, specially-constructed bullets were often "paper patched", or wrapped in a couple of layers of thin paper. This patch served to seal the bore and keep the soft lead bullet from coming in contact with the bore, preventing leading (see internal ballistics). Like the cloth or paper patch used in muzzleloading firearms, the paper patch fell off soon after the bullet left the bore. Paper-patched bullets were made of soft lead .450 inches (11.4 mm) in diameter. When wrapped in two layers of thin cotton paper, this produced a final size of .458 inches (11.6 mm) to match the bore. Paper patched bullets are still available, and some black-powder shooters still "roll their own" paper patched bullets for hunting and competitive shooting. Arsenal loadings for the .45-70-405 and .45-70-500 government cartridges generally used groove diameter grease groove bullets of .458 inches (11.6 mm) diameter.