I just purchased a used Glock-26, it was made 7 years ago and was a back-up gun for a corrections officer. shot 50 rds. through it in all that time, practically a new gun. the slide has a strange finish, one that ive never seen before. It looks like its painted flat black. Gun dealer says it is a melonite coating. what is that? Is it any good? It seems on the rough side, and i dont know how well it wears. need some help on this one.