Last year I was on a shotgun course, after a couple of hours the instructor comes along with a squirty bottle thing and we all oil up the working parts, same again in the afternoon. I mention gun oil cost and he says it only costs a couple of dollars for a pint. What is it? Automatic transmission oil mixed with 10% engine oil. Used by many a police department, Federal Agency armory and issued in cleaning kits. Turns out its one of those things that "those in the know" have known for ages and that the difference between automatic transmission oil and gun oil is so fine that you could'nt squeeze a fag paper between them. Now tell me you all knew.