Bill,

It appears you have obediance, gunfire and exposure to water under control, so my advice would be introduction to birds. The dog is definitely trainable at six years of age (Chesseis are very intelligent). Continue working the dog as you have, get birds " in her system" and everything should fall into play. Repetition is the key -- along with exposure to birds. Just remember plenty of praise and do not be too hard on the dog. Chessies can be very unforgiving