I have been shooting the AR15 since 1976 and have never seen, nor talked to anyone whom has seen a "slam fire", and in my 20 years as a Police Officer, 18 1/2 years of those were as a weapons instructor. I have seen thousands of "rounds a day" and have never seen one, and only saw one malfunction in the AR, and that was an officer had a dry bolt and when it got hot, it quit. What I have seen, AND EXPERIENCED, is stretched primer pockets where the AR blew the primer out of the pocket during cycling and locked the bolt cluster up, causing one to have to tear the rifle down to free up the bolt.