I've had some success for my hand with radiation induced bracial plexus -- my hand/arm went from totally numb couldn't lift my coffee cup and hold a pen to thumb/pointer numbness but able to do most stuff.

I did OT, PT, steroids, Vit B and Trental, and 40 rounds of Hyperbaric Oxygen Therapy.

The hyperbaric was a long shot, and it took a couple tries to get insurance to accept it, but it helped the most.

I am so sorry about your gunshot wound and I hope something on this list could help.