Originally Posted by ex_code_jock
The only delta spouts I have ever seen are screw on ones, that does not mean that there arent others out there, but if there is no set screw underneath then it has to be screwed on to pipe threads.
If it is on with a set screw and you turned it somewhat, you would hear that set screw scraping against the copper as it turns.
This thing is going to be on in one of the following ways:
Set screwed onto raw copper tubing, in which case turning it too hard could distort the tube.
There could be a male adapter at the end of copper tubing that it is screwed onto, you could break the solder joints
If its a brass nipple (which i think it probably is) the worst you could do is end up unscrewing the nipple from the bath/shower unit behind the wall, which would could just thread back in