The .45-70 Government black powder military cartridge was first offered in the US Model 1873 Springfield Trapdoor rifle. It was soon offered in a variety of sporting rifles, where it remains popular today among big game hunters and target competitors.

Industry maximum average pressure for the .45-70 is established at 28,000 CUP; however, most of today’s SAAMI specification factory loads hover around 20,000 CUP in deference to older black powder-era rifles and their weaker actions, along with certain modern production firearms.

Most handloading manuals divide .45-70 data into three categories. "Category 1" is for the US Model 1873 Trapdoor rifles and actions of similar strength, and should never exceed pressure guidelines of 28,000 CUP. "Category 2" is for stronger actions, with some referring to it as "Lever Action" or "Modern Marlin Model 1895" data, which is generally loaded to between 35,000 to 43,000 CUP (depending on source). "Category 3" is for actions designed to withstand the pressures associated with modern high-pressure cartridges. Examples include the Ruger No. 1, Browning Model 78, Winchester/Browning Model 1885 (modern version ONLY), Siamese Mauser and Wickliffe. All data listed in the accompanying charts are "Category 3" loads, which have been tested at a maximum pressure of 50,000 CUP. These loads should never be used in guns of lesser strength.

Due to the short throat of several Ruger No. 1 rifles tried, the Hornady 350-grain flat point and 500-grain DGS and DGX bullets would not chamber when seated to listed overall cartridge lengths. A bit of research proved that Ruger has used at least 2 different throat lengths, with the "long throated" version allowing the above cartridges to readily chamber. Our test rifle was manufactured during the late 1970s and featured the long throat. Incidentally, three modern Browning/Winchester Model 1885 rifles were likewise tried, all of which featured a short throat and would not allow cartridges loaded to the listed specifications to chamber. In either case, a qualified gunsmith can open (or lengthen) the throat, allowing them to chamber handloads listed herein.

The most accurate powders included IMR-4198, IMR-3031, Hodgdon H-322 and Accurate 2015.

Velocities with the 350-grain Hornady FP bullet reached over 2,200 fps, while the 500-grain DGX reached nearly 1,800 fps. Again, these loads should never be fired in guns other than those listed here. And as always, begin with starting powder charges and work up carefully to maximum loads.