The end of the civil war left huge quantities of surplus military equipment in the Government stocks. The war that took more than 600.000 thousand American lives saw a great number of new inventions on the battlefield including the repeating rifles firing self-contained metallic cartridges. The war ended and the Government with exhausted finances was not keen on spending money on anything that was designed for killing. While in Europe great changes were taking place in infantry tactics. The battle of Königgrätz in 1866 between the Hapsburg Monarchy and the Prussian Kingdom marked the end of the era of the muzzleloaders. The needle firing rifles of the Prussian soldiers were clearly superior compared to the Lorenz rifles of the old Monarchy. The breech loading mechanism multiplied the firing rate of the soldier. While a rifle-musket armed soldier was capable of 3 shots per minute the soldier with a breech loading rifle fired 12. This also marked the end of closed infantry formations on the battlefield.
In the second half of the 1860s all modern armies were looking for a replacement for the muzzleloading system. The self-contained cartridges also saw a great development. With the appearance of the centre fire systems of Hiram Berdan and Edward Mounier Boxer it was time to eliminate the weak rim-fire ammo from military service. The rim-fire cartridges had limited power, as the casing had to be soft enough to allow the hammer to set off the priming compound pressed into the rim of the cartridge. This made the extraction unreliable, as the extractor could jump over the easily deforming rim, leaving the fired case in the chamber. The charge of the rim-fire cartridge had to be limited, as the weak case could not withstand high pressures. Berdan and Boxer offered a good solution to the problem: they placed the primer into the thick base of the case with a touch hole leading to the main charge. Their cases could be harder, and could hold higher charges.
Some video coverage of our Trapdoors:
The bore and bullet diameters were changing also. The first small calibre muzzle loading military rifle was the Swiss Model 1851 Eidgenössische Stützer or Feldstützer. This .41 cal rifle fired a patched conical bullet called the Buholzer-Minié. In England, a talented engineer, Sir Joseph Whitworth was also experimenting with small calibres and fast twist bores. His rifle with a .451 bore firing a mechanically fitting hexagonal bullet, and various other British sniper rifles like the Kerr proved very effective tool against Union officers. The new system expanded the effective range of the rifle to nearly 1000 yards – of course only in the hands of the well trained soldier.
The US Government was slow in the process in changing the standard issue military rifle to a breech loader. The cost effective way of this transformation was to keep and modify what they already had, the Springfield rifle-muskets. This was not uncommon. All modern armies were facing the same problem. In 1856 Erskine S. Allin, head armourer of the Springfield Arsenal was commissioned to design a solution to transform these rifles into breech loaders the cheapest possible way. What he did was simple: he milled out the top section of the breech and attached a vertically opening door system. His first samples fired a .58 cal rim-fire cartridge.
In 1866 he made some improvements to the design. He understood the need for a smaller and stronger calibre. His new rifles were chambered for the .50-70 centre fire cartridge. He reamed out the .58 cal barrels and inserted a .50 cal liner to reduce the diameter of the bore. But this was not the end of the development. In the following years he continued the work with replacing the sleeved barrels with newly made .50cal barrels. His breech was also perfected within the following years.
In 1872 the Board of Ordnance was ready to make a decision. 99 rifles were competing against each other, including the famous Remington Rolling Block, the Peabody, the Sharps, the Whitney, etc… They chose the sample rifle submitted for the tests called “No. 99”. This single shot rifle featured an improved Allin type breech. This action was a separate part of the barrel. The receiver was crewed on the breech. The new cartridge to be adopted was also a better design compared to the 50-70. The .45-70 had a better ballistic performance with higher velocity and lower trajectory.
The Model 1873 Springfield “Trapdoor” rifle and the .45-70-405 (.45 = the calibre of the bullet, 70=the black powder charge, 405=the weight of the lead bullet in grains) ammo was accepted for military service and proved a reliable high power combo on the frontiers. There were some minor changes in the design during its nearly 20 years of service. It became obsolete by the adaptation of the Model 1892 Krag-Jörgensen repeating rifle. The mark of a new age again.