I have never dealt with an AR 15 so I am not sure how different they are from the m16 or m4, but my piece of advice is, accessories are expensive, 550 cord is not. Don't be shy about tying down your scope, CCO, or other accessories so that if a screw comes loose you are not donating a several hundred dollar piece of equipment to mother nature.
"A fear of weapons is a sign of retarded sexual and emotional maturity." Sigmund Freud in "General Introduction to Psychoanalysis"
"My dear boy, I love hearing my relations abused. It is the only thing that makes me put up with them at all. Relations are simply a tedious pack of people, who havent got the remotest knowledge of how to live, nor the smallest instinct about when to die."