John W. Keene was an independent gun designer who developed this rifle (and took out 9 patents on its various features) in the 1870s. He did not have a factory at his disposal to produce the gun, so he went looking for manufacturing partners. The Remington company at that time had been heavily committed to their very successful single-shot Rolling Block rifle, and did not have a bolt action design to submit to the upcoming 1878 US Army rifle trials. This was a natural fit, and Remington bought the rights to make Keene's rifle.
The Remington-Keene did not manage to win adoption at the 1878 trials (no rifle did, in fact), but it did attract the interest of the US Navy, and Remington also decided to offer it for commercial sale (as was common of repeating rifle designs at the time which had been rejected by the Army). The Navy purchased 250 examples in the early 1880s and issued them to the USS Michigan and USS Trenton. On the commercial side, the rifle remained in production from 1880 until 1888 with about 5,000 being manufactured and sold. It was offered in a variety of barrel lengths and configurations, and in three different calibers (.40-60, .43 Spanish, and .45-70) - although the .45-70 chambering was by far the most popular.
The Bureau of Indian Affairs also purchased between 600 and 800 Remington-Keene carbines, and they were used by Indian Agents and tribal police forces.
Cool Forgotten Weapons merch! http://shop.bbtv.com/collections/forgotten-weapons
If you enjoy Forgotten Weapons, check out its sister channel, InRangeTV! http://www.youtube.com/InRangeTVShow