I have a axis less bolt that I would like to use for a project, but getting a replacement bolt here in Oz seems to be bit of a problem. I seem to be able to source all the bits needed from Brownells but not the main bolt tube which I think I can make my self. This leads to my question in reguards to bolt heads and the rotating one behind the front head. Are there any compatable heads from other models such as model 10 ,12 etc?