The Springfield Model 1870 Remington-Navy was a breechloading rifle intended to be used by the United States Navy. The Model 1870 incorporated the Springfield Armory's Model 1868 frame, barrel and stock with the Joseph Rider designed Remington Rolling block.
The Model 1870 was heavily based on the Model 1868, one of the 'Trapdoor' Springfields (using the Erskine S. Allin designed hinged breechblock concept to open and close the breech). Therefore the Model 1870 used the same stock (although some were modified in shape to reduce the overall length of the Model 1870), 33in rifled barrel and basic frame design. The same cartridge was also used for the Model 1870 (the .50-70 Government).
However the key aspect of the Model 1870 was the Remington style rolling block mechanism, originally designed by Joseph Rider. This mechanism differed from the 'Trapdoor' design as the breech was closed by a rotating block, rather than the block moving away on a hinge. Nonetheless, both designs were designed to allow the shooter to load the new cartridge from the rear of the firearm, and it just so happened that the rolling block design suited the US Navy's needs.
The Model 1870 was designed to use the .50-70 Government cartridge, designed by the Springfield Armory for the Model 1866. This cartridge was chosen for two main reasons. Firstly the Armory already produced it, and secondly the .50 calibre cartridge was already in use by the US Army (with the various evolutions of the 'Trapdoor' Springfield.
The Model 1870 was originally commissioned by the US Navy after a few years of testing of various breechloading rifles. The Navy Bureau of Ordnance chose the Rider design after two years of testing the rolling block concept, although they requested that the resulting rifle be built at the Springfield Armory rather than by Remington (whom owned the rights for Rider's design). The dispute resulted in the Armory producing the Model 1870 entirely, although Remington would receive $1.00 per rifle built.
The Navy ordered 10,000 Model 1870s, all of which were delivered within a year. However the inspectors discovered that the rear sight was positioned incorrectly (it had been mounted too far forward, directly infront of the chamber, and was therefore deemed unsafe for use). Therefore the rifles were sold to Poultney and Trimble of Baltimore (whom exported the rifles to France during the Franco-Prussian War). The money generated from the sale of the defective of rifles was enough for the US Navy to order 12,000 "Type II" Model 1870's, which incorporated the improvements specified by the inspectors.