just a tip, but if you put some lube on the end of your air tank, it screws in a lot easier.
I wouldnt put anything like that near where it could possibly get into your tank. Do a search for the exploding tank and why it exploded and caught on fire.
i thought that was only the fill nipple. "Mike from TechPB" says that if you put it on the end of the reg it will be fine. but he could be wrong. Also, if you put it on the threads of the gun asa it will be fine, right