Shooting.... is this about having live birds driven to you or flushed up as you walk, or is it about hitting clay targets fired up to represent the different flights of game birds? Trap shooting is a commonwealth (and olympic) sport which has developed out of a field sport which it was one part of. Target shooting is a development of stalking/hunting. So why not competitive casting?
Playing devils advocate there is no way the anti brigade could have any problem with a casting competition, they sure as hell do with fishing competitions?