The rifle first became familiar during the Vietnam War, through grainy, televised images of the M-16, which was the military version of the AR-15. That was followed by a string of high-profile incidents and movies such as “Rambo” in the 1980s, an end to imports of the Uzi and the AK-47 in 1989 and a partial federal ban on semi-automatic firearms in 1994, the wars in Iraq and Afghanistan, with returning servicemen eager to have their own versions of the rifles they carried and increasing use of realistic video games and a target-shooting sport called “three-gun competition."