I was looking into have my A-5 dipped but just couldn't bring myself to do it. But I did a lot of research and found trebark to be excellent, Here's the address trebark
I don't think the internal parts are affected by the dipping. How old is the gun you want to do this with? How much do they want to dip it? I have always done my own with a camo spray kit but they have been older guns with a lot of use.