I believe that Ron has correctly identified this 1887 specimen.
However, Gourd has got it at least part right as well, although the 1887 production of Morse patent cases is obviously something new to him.
George Morse was a clever inventor. He invented a design for the Model 1816 .69 caliber flintlock muskets which converted them to breechloaders using a .69 caliber centerfire cartridge. Around 650 were made just prior to the Civil War but work stopped when the war broke out, and those being converted at Harpers Ferry were destroyed when that armory was burned. (I’d like to get one!)
During the Civil War, Morse cast his lot with the south, and ended up working at the South Carolina State Works in Greenville, SC. There he produced an entirely different design .50 caliber breechloading carbine, again using a centerfire cartridge, making about 1,000. In 1864, Morse began making “Inside Lock” muskets at the State Works which featured a novel lock needed fewer parts. These were otherwise fairly conventional muzzle loading muskets, not breechloaders.
After the Civil War, in the 1870s, Morse got involved with Andrew Burgess and the Whitney Firearms Company making lever action rifles- The Whitney-Morse-Burgess model.
So, there are a variety of cartridges related to Morse, the .69 breechloader, the .50 caliber carbine and the 1887 vintage Frankford Arsenal ammo made on his patent.
I hope someone will post examples of the first two.