http://muzzleloader.i.am/ is the Traditional Muzzle Loader Hide. These guys are into tanning deer, making horns and other nifty things related to black powder rifles. They also go to Friendship, IN a lot and to the Dixon Gunmaker's fair.
I also visit the North South Skirmish Association site for stuff on the Civil War as well as Joe Bilby's Civil War Guns site.
These three cover a lot more than hunting on their respective ML forums, in fact hunting tends to be a secondary topic, with muzzleloaders the primary.