It's been 12 years or so. I think I used Zip Strip, a common finish remover. It was a hard decision but the "paint" chiping off the grip frame was 'bout to drive me nuts. I'm happy with it and haven't looked back.
If you realy want to keep the finish, remove the grip frame, strip it and have someone apply a Urethane finish or powder coat. Remember to watch the dimensions where the grip frame fits to the gun too many mils of any coating may make the fit a booger. Urethane or powder will be durable and available local.
If you really want to get fancy. call up Robar and see what they can do.
www.robarguns.com