I have a BCD4 98k and I wanted to refinish the steel on it. The finish is coming off of it and I would like to repair it. The receiver and barrel have pitting on the outside although before I got it all of the rust had been cleaned out. I was hoping someone could give me advice on how to fill the pitting and then finish it off with something protective. I have looked at duracoat products because they also have a filler that is made for pitting. But I'm not sure yet. I would probably have to take down the whole gun and blast it off first. Does anyone know what parts get finished besides what you can see on the outside? Am I supposed to fully strip the gun and cover every part inside too? Or just what you see on the outside of the gun?