a5 paint repair

I recently bought a used and very abused A5.

The marker hadnt been cleaned in quite a while (covered in old paint), and the original black is coming off.  It's stripping off almost like paint remover had come into contact with it in several odd places(This isn't the whole gun- mostly along the rail and the pin holes).

 

Does anyone know of how this can be best repaired without completely stripping the marker and repainting it? I'd like to keep a fairly durable coat on it if possible.

 

The stock paint job on it is very bad. They didn't use any type of priming so the paint easily peels off from the alluminum. I would suggest just totally redoing it. It will look much better than trying to repair it all. I would say repainting it with something like car spraypaint will cost about $20-30. If you do repaint it, use self-etching primer that way the paint will have something to adhere to because the primer actually digs into the surface.