Black powder cartridge rifle enthusiasts are directed to BPCR.net, a site "dedicated to shooting and enjoying the black powder cartridge rifle." Associated with the web site is an email discussion list and web based forum which cover all aspects of BPCR shooting.
 
Long Range BPCR is "a resource for both the new and experienced shooter who is interested in competing in Long Range BPCR events (800, 900, and 1,000 yards)."
 
The Shiloh Sharps Rifles web site has a user forum with lively discussion on the BPCR.
 
David