The .45-70 Government
By Chuck Hawks
The traditional .45-70 factory load is a 405 grain bullet (BC .214, SD .272) at a MV of 1330 fps, and a ME of 1590 ft. lbs. This is a very moderate load that kills well because of the penetration of its big, heavy bullet. It has been used on all North American game, but today should be restricted to use at close range.
In an attempt to improve the low pressure .45-70 load, the factories have been loading a 300 grain JHP bullet (BC .171, SD .204) at around 1,810 fps. At that velocity, according to Remington figures, the ME is 2182 ft. lbs.
The trajectory of this load allows a scoped rifle to be sighted as follows: +3" at 82 yards, +2.7" at 100 yards, -3" at 162 yards, and -10.2" at 200 yards. This makes the 45-70 about a 162 yard rifle for use on deer size game.
Pertinent information about the .45-70 includes that it accepts standard .458" diameter bullets, has a COL of 2.55", a maximum case length of 2.105", and a SAAMI MAP of 28,000 cup.
Reloaders with modern single shot rifles can safely exceed the official COL as long as the bullet is not jammed into the rifling when the cartridge is chambered. The bullets in reloads to be used in magazine fed rifles are usually roll crimped in place, but loads intended for single shot rifles need not be crimped.
Handloaders with modern Marlin lever action rifles have pioneered the use of high pressure (+P) .45-70 loads, as the modern Marlin 1895 action is much stronger than the Trapdoor Springfield action or reproductions there of. Lever action rifles are limited to bullets weighing about 400 grains, as heavier (and thus longer) bullets will not feed through their actions.
The owners of modern single shot rifles, such as the Ruger No. 1 and Browning 1885 High Wall, can safely take the pressure limit even higher, and can use 500 grain bullets. The result is loads that tread on the heels of some African safari cartridges.
The handloader will normally load bullets of 300, 350, 400 and 500 grains, although other bullet weights in the same general ballpark are available. I have had some experience reloading the .45-70 with all of the above bullets, and I have found that IMR 3031, a traditional powder choice for the cartridge, gives excellent performance with all bullet weights.
According to the sixth edition of the Hornady Handbook of Cartridge Reloading, 40.9 grains of IMR 3031 powder can drive a Hornady 300 grain JHP bullet to a MV of 1300 fps, and 52.0 grains of IMR 3031 can drive the same bullet to a MV of 1800 fps. This essentially duplicates the factory loads, and does not exceed the SAAMI specified MAP. These and the Hornady loads to follow used Winchester brass and Federal 210 primers.
The second level of loads are for modern Marlin 1895 lever action rifles. In these loads pressures can run up to 40,000 cup. These reloads can drive a Hornady 350 grain bullet to a MV of 1400 fps with 45.2 grains of IMR 3031 powder, and a MV of 1900 fps in front of 56.1 grains of IMR 3031. These velocities were taken in the 22" barrel of a Marlin 1895 rifle. According to the Hornady Handbook, Sixth Edition, these loads are adequate for ". . . any North American game at moderate range."
The final selection of .45-70 reloads are for strong bolt action or single shot rifles that can take pressures running up to 50,000 cup. In such rifles 55.4 grains of IMR 3031 can give the Hornady 350 grain bullets a MV of 2000 fps, and 59.6 grains a MV of 2200 fps. These loads were chronographed in the 22" barrel of a Ruger No.1 rifle.
For the utmost in penetration on very large animals, the 500 grain Hornady RN or FMJ-RN bullets on top of 44.1 grains of IMR 3031 results in a MV of 1500 fps, and a maximum load of 53.1 grains of IMR 3031 can drive these 500 grain bullets to a MV of 1800 fps. Again, these high pressure loads were tested from the 22" barrel of a Ruger No. 1 rifle.
I can tell you from experience that these heavy loads kick like the devil, but they make the .45-70 a serious "stopping" caliber.
Note: A full length article about the .45-70 Government can be found on the Rifle Cartridge Page.
Copyright 2004 by Chuck Hawks. All rights reserved.