The 300 grain Hornady FPB holds a lot of promise:

http://www.hornady.com/store/50-Cal-300-gr-FPB



The Hornady Great Plains bullets are also a long time favorite for their accuracy and are devasting on deer, but they are harder to load.

http://www.hornady.com/store/50-Cal-c-674/

There may also be something to try out in a 1 in 48" Deer hunter flintlock in this thread:

http://huntingnet.com/forum/black-po...nd-1-48-a.html