Unusual Antique Shot Flask, Horn with Leather

This is an unusual shot flask and I cannot find a comparison, sadly there are no makers marks which would have helped, at first glance it appears a regular leather covered shot flask but as the leather has shrunk and moved with age you can see that the body is made from horn, the edges have been finished with metal and then leather covered, the top end fitments are brass, it has a flat back and a distinct domed front. Condition wise its not at its best, the metal clip on the top doesn't work and the leather has a large hole on the back probably caused by storage over the years, it measures 7.25 inches long.