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.45-70

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The .45-70 rifle cartridge was developed at the US Army's Springfield Armory for use in the Springfield Model 1873 .45 caliber rifle, known to collectors (but never to the Army) as the "Trapdoor Springfield." The new cartridge was a replacement for the stop-gap .50-70 cartridge which had been adopted in 1866, one year after the end of the American Civil War.

Nomenclature

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

  • .45 : nominal caliber, in decimal inches i.e. 0.45 inches (11.4 mm)
  • 70 : weight of propellant (black powder) charge, in grains i.e. 70 grains (4.5 g)
  • 405 : weight of lead bullet, in grains i.e. 405 grains (26.2 g)

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 3,500 yards (3200 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. At those ranges, the bullets struck point-first at roughly a 30 degree angle, penetrating 3 one 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 volleyed fire at ranges beyond those normally expected of infantry fire.

Note that while the nominal bullet diameter was .45 inches, the bore was actually closer to .458 inches (11.6 m). Arsenal loadings for the 45-70-405 and 500 government cartridges generally used bore diameter grease groove bullets of .457-.458 diameter. As was standard practice with many early U.S. commercially produced cartridges, 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 are still available, and some black powder shooters still "roll their own" paper patched bullets for hunting and competitive shooting.

History

The predecessor to the .45-70 was the short lived .50-70-425 cartridge, adopted in 1866 and used in a variety of rifles, many of them percussion rifled muskets converted to trapdoor action breechloaders. The conversion consisted of milling out the rear of the barrel for the tilting breechblock, and placing a .50 caliber "liner" barrel inside the .58 caliber barrel. The .50-70 was popular among hunters, as the bigger .50 caliber bullet hit harder (see terminal ballistics) but the military decided even as early as 1866 that a .45 caliber bullet would provide increased range, penetration and accuracy. The .50-70 was adpoted anyway, as a stopgap until a significantly improved rifle and cartridge were developed.

The result of the quest for a more accurate, flatter shooting .45 caliber cartridge and firearm was the Springfield Trapdoor rifle. Like the .50-70 before, it, the .45-70 used a brass center-fire case design. A reduced power 55 grain loading was also adopted for use in the Trapdoor carbine. This had a 55 grain (3.6 g) powder charge.

It was last used in quantity during the Spanish-American War, and was not completely purged from the inventory until well into the 20th century. The rifle itself underwent a number of modifications over the years, the principal one being a strengthened breech starting in 1884. A new, 500 grain (32 g) bullet was adopted in that year for use in the stronger arm. The .45-70 rifle was the principal arm of the US Army until 1893, long after European adoption of efficient repeaters using smokeless powder ammunition had made the American weapon obsolete as a military rifle.

The .45-70 is still used by the military today, in the form if the CARTRIDGE, CALIBER .45, LINE THROWING, M32, a blank cartridge which is used in a number of models of line throwing guns used by the Navy and Coast Guard. Early models of these line throwing guns were made from modified Trapdoor and Sharps rifles, while later models are built on break-open single-shot rifle actions.

Sporting use

A long range tang sight, commonly used on black powder cartridge rifles

As is usual with military ammunitions, the .45-70 was an immediate hit among sportsmen as well, and the .45-70 has survived for one and a third centuries. Today, the traditional 405 grain (26.2 g) load is considered adequate for any North American big game within its range limitations, including the great bears, and it does not destroy edible meat on smaller animals such as deer due to the bullet's low velocity. It is very good for big game hunting in brush or heavy timber where the range is usually short.

A graph showing the relative trajectories of the .45-70-405 and the 7.62x51 mm/.308 Winchester out to 1500 yards

The main limitation of the .45-70 is the relatively low velocity which puts a practical limit on shots at game beyond 120 meters or so, despite its ability to kill at many times that distance. The trajectory of the bullets is very steep, which makes for a very short point blank range. This was not a significant problem in the Old West, as the .45-70 was a fairly flat-shooting cartridge for its time, and shooters had to be keen judges of distance, wind and trajectory to make long shots. Most modern shooters use much higher velocity cartridges, relying on the long point blank range, and rarely using telescopic sight's elevation adjustments, calibrated iron sights, or hold-over. Sights found on early cartridge hunting rifles were quite sophisticated, with a long sighting radius, wide range of elevation, and vernier adjustments to allow precise calibration of the sights for a given range. Even the military "ladder" type rifle sights were calibrated and designed to handle extended ranges, flipping up to provide several degrees of elevation adjustment if needed. The .45-70 is a popular choice for black powder cartridge shooting events, and replicas of most of the early rifles, including Trapdoor, Sharps, and Remington single shot rifles, are readily available.

The .45-70 retains great popularity among American hunters for the niche it is suited for, and is still offered by several commercial ammunition manufacturers. Although loaded with modern smokeless powders, in most cases (but not all: read the box!), pressures are kept low for safety in antique rifles and their replicas. Various modern sporting rifles are chambered for the .45-70, and some of these will benefit from judicious handloading of home-made ammunition with markedly higher pressure and ballistic performance. Others, which reproduce the original designs will take the original load, but are not strong enough for anything with higher pressure. You MUST know your rifle and whether it will take the heavy loads. In a rifle such as the Siamese Mauser or a Ruger single shot, it can be handloaded to deliver good performance even on big African game. Never shoot such loads in rifles that were not designed for such pressure, such as original or modern reproduction trapdoor Springfields.

In addition to its traditional use in rifles, Thompson Center Arms has offered a .45-70 barrel in both pistol and rifle lengths for their Contender single shot pistol, arguably the most potent caliber offered in the Contender frame. Even the shortest barrel, 14 inches, is easily capable of producing over well over 2000 ft. lbs. of energy, double the power of most .44 Magnum loadings. Recent .45-70 barrels are available with an efficient muzzle brake that significantly reduces the muzzle rise and also helps attenuate the tremendous recoil, but the recoil is still punishing. Only with the recent introduction of ultra-magnum revolver cartridges such as the .500 S&W have production handguns began to eclipse the .45-70 Contender in the rareified field of big-game capable handguns.

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