Below are a series of links to forums I have found useful over the last year or so. Most require membership but this is simple to do and free.

Research Press Forum

Muzzle Loading Association of Great Britain

Full-Bore, A great UK based forum

Enfield-Rifles, Dedicated to Enfield Rifles, with an emphasis on the .303 variety

British Militaria Forums

Military Surplus Collectors Forums

Gun Boards

Curio And Relic Firearms Forum

Castboolits -A forum dedicated to bullet moulding

The High Road.Org