Much information has been published on long range muzzle loading, however the sources are diverse and many. LRML.org maintains a Resource List to aid readers in researching the subject. Please contact me if you can add to this list.
 
The Muzzle Loaders Association of Great Britain was formed in 1952 and is the Governing Body for muzzle loading within the UK. The Association holds National Rifle Championship matches at 200, 300, 500, 600, 900 and 1000 yards. In addition members of the Long Range Rifles Branch of the MLAGB shoot muzzle loading percussion rifles at ranges usually commencing at 600 yards. Training shoots are held, and the match schedule includes the coveted Metford Trophy, fired at 1000, 1100 and 1200 yards.  
 
David