This carbine is lot #1416 at Morphy's April 2019 auction:

https://auctions.morphyauctions.com/_AVERY_RARE_ARMSTRONG_TAYLOR_SWIVEL_BREECH_SIN-LOT459300.aspx

The Armstrong & Taylor carbine is a neat single shot breechloading carbine patented in 1862. It operates by way of a button on the top of the rear tang, which allows the barrel assembly to rotate open around a pin located below the barrel. An extractor is mechanically camel to the pin, and pushes the empty cartridge case out as the barrel assembly rotates. The inventors were clearly hoping for a military contract, but were unable to supply the gun to the government until after the Civil War had ended. Instead, it was entered in the 1866 breechloading rifle trials, where it was eliminated (along with 21 other designs) in the first round of trials. It managed to fire 100 rounds of .41 rimfire ammunition at a rate of 14 rounds per minute, but was considered unsuitable. The trials would eventually choose the Allin Conversion as their winner, better known as the Trapdoor Springfield.