Found this earlier today - super cool design. The guy who built it has all sorts of cool muzzle-loader projects on his site.
http://www.ctmuzzleloaders.com/ctml_experiments/lorgir_pistol/lorgir_pistol.html
https://www.youtube.com/watch?v=GWXiIqh0DwQ&feature=youtu.be
http://www.ctmuzzleloaders.com/ctml_experiments/lorgir_pistol/lorgir_pistol.html
https://www.youtube.com/watch?v=GWXiIqh0DwQ&feature=youtu.be