The only time its to late to train a dog is when there ashes are in a jar above the fireplace.
Intro to birds and gun is biggest hurdle. Theres a way to do it that 99.9% of the time is fool proof. but it has to be done right or you wind up with gun shy.
Sounds like the dog wants to be a hunter, you just need to guide him thru it.
My advise is to find a trainer in your area to help you train your dog. Most trainers only charge about 50 dollers an hour plus birds. With just a few trips it will get you of in the right direction and get you well on the way to a fine hunting partner.
You will be amazed at what a pro can do with your dog in short time frame.