A friend of mine is telling me that he is going to turn his AR-15 (Primary Weapons System) into a semi auto, 3 round burst, and / or full auto AR just by buying a new trigger. He was saying a SSA stage 2 trigger would allow him full auto or 3 rounds burst. I explained to him all he is doing is installing a better trigger than what came with it from the factory. I told him there is no F'ing way that just replacing your trigger will make your AR full auto. I mean if it did than everyone and their brother would have a full auto AR. I told him from what I have seen / heard a full auto colt M4 is 8-15K plus the stamps. But he seems to think because he has a piston driven upper that all he needs is a new trigger. I believe he is full of **** but to be honest I don't know to much about full auto parts and / or rifles. Can someone give me a list of parts that he would need and a rough estimate for total cost to convert an AR-15 into 3 round burst or full auto? I'm tired of hearing him tell everyone that he is about to have a full auto AR