I was out at the range today with two other guys at the adjacant spot about 200 yards away. I heard a single shot and HUGE KABOOOOOOOM!!!! Made me jump. Then while I was thinking that could have been a tannerite explosion I hear this volley of shots that sounded like an automatic weapon. I thought...WHOA!!!! Curiosity got the best of me. I went over there and sure enough 1/4 pound of tannerite was the cause of the explosion. Both guys were shooting AR type weapons. I struck up a conversation with them and learned one guy had an attachment to his weapon that causes the trigger to continue to cycle by holding the trigger back. He had a certificate of sorts from the manufactor that stated it was completely legal as it was an external attachment. Let let rip with another volley and I swear it acted JUST like a full auto. Pretty cool to see the brass flying out and dirt kicking up. Any of you AR fans know of this? I guess I should have gotten the name of it but it was mounted on the right side and there was a hook like shoe that fitted over the trigger.