Hmmmmmm? The coefficient refriction as much as I want to belive I am a Master of a AR-15 rifle some thing new pops up. I will do my home work and get back to you. I guess they(US Army, DPMS or The Man) never gave me the hand out on that question. But rest assure I will find the knowledge. As Master Yoda once said Do or do not there is not try. I understand that all things are very Important and I do not want to upset you my young padawan but today is Too soon and I hope tomorrow brings great light to this subject.