Until Royal Purple introduced a specific Gun Oil, I used RG21 for all lubrication except AR and Benelli bolt carriers.
http://www.rpmoil.com/images/gunoillowrez.jpg
http://www.rpmoil.com/images/sqts13lg[1].jpg
They do the job and are the only pure synthetic oil I can find. Mobil One is not pure synthetic.
Anybody else use Royal Purple?