These are a few of the links I have gathered. Most of them relate to shooting, all of them are useful.
Muzzle Loaders Association of Great Britain
Muzzle Loaders Association of Great Britain – Thames Estuary Branch – This is Jeff & James’ local branch
The Muzzle Loaders Associations International Committee
National Rifle Association USA
Muzzle Loaders Association of Great Britain – Surrey Branch
Basildon Rifle and Pistol Club – This is Jeff & James’ local club
Single Shot Black Powder Cartridge Rifle Club UK
Other Shooting Interest
Black Powder Journal – USA muzzle leading articles
David Minshall’s research notes – Everything you need to know.
The Flintknapper – Germany’s leading Muzzle Loading supplier
svartkrutt – A portal for black powder shooters and collectors
Medieval Gonne Works – A site dedicated to the revival if Medieval Firearms known as Handgonnes