Long time inactive member, first time posting. Please forgive any lapse in judgment on my part. I have never had any desire to own an AR15 but I Am beginning to get curious as to why they are so popular. Being a handy kind of guy the whole "Lego" aspect is also attractive to me. The biggest problem is that I don't know anything about how they work. Is there a good book on how they work and building one for a newbie? Thanks for any recommendations.