I am trying to install a A.R.M.S. 50M and have to remove the barrel to get the Delta ring and compression spring off. I have never done this so I am a little hesitant and need some more info. can I just unscrew the barrel nut from the reciever or is there a detent or anything else I should know about before wrenching on the barrel nut. Thanks. Also I scratched the shit out of the gas tube pulling it out, is there any esy way to do that? Any guidance or input is helpful.  

After you remove the gas tube, just unscew the barrel nut. Some are on pretty tight and I have seen some that came off with just finger pressure.

Make sure you are applying pressure on the delta ring when you're trying to unscrew the barrel nut.  The delta ring and weld springs will try to push the wrench off the barrel nut teeth sometimes.  If you're not careful you could round off some teeth.  MJD