It dosen't quite work like that, I do my own. There are places that offer replacement of the crosshairs but these scopes are under warranty so weigh the risk if you chose. I'm sure if it gets sent back and they see someones modified it, you might have problems. Can't tell you much about parts, there are a couple places that do work on Unertls but I'd have to dig through my notes, I can't think of the name right now.