Guns, Dogs and Blades QnA
Might try some polishing compound on the areas that aren't checkered? Maybe start with 600/800 grit paper and progress to 2000, then the polishing compound. That's how I do headlight lenses and it works good. Looks ugly for a while until you get to the finer stuff. Try on the inside surface first. Don't know what material the grip are but mechanical means is the only way I would try it.