AR-15 guys, I recently bought a cheap AR-15 Carbine on Gunbroker, brand NiB. When I took it to the range to test it out, it fires when the trigger is pulled (as it should) then when you release the trigger to reset for another shot, it fires again. Any ideas? and no I don't want to send it back. Is there a part in the trigger group I could just replace? or would I need to replace the entire trigger group? thanks.