I cured a lab of being gunshy once but as much time as it takes and as iffy as it is I would recommend finding a good for this one and starting with a new pup. If you choose not to do this, then get her retrieving built up to a fever pitch (and this not done just by throwing a dummy} then always make a lot of noise when she does make the retrieve. Gradually when she is no longer paying any attention to the noise you may start with a .22 and shoot away from her. Eventually you will have to switch to a shotgun and again do not shoot over the dog. Shoot away from her as she is going to make a retrieve. There is a lot more to this but mostly just common sense and the patience of Job. Good luck.