Yes, man had the legal right to do it. However, why does the state allow that right?
A Brief History Of The AR-15 : NPR
Huge problem': Passengers are bringing a record number of guns to the airport, TSA says, Archive
Man with AR-15-style rifle near bus stop claims he wasn't trying to terrify kids - The Washington Post
How the AR-15 Became an American Brand
Out of the Box: How to Rebalance U.S. Somalia Policy
AK-47 and its extended family Quiz, Equipment & Weaponry
What are the Loudest Guns?
Letter: Founding Fathers said nothing about AK-47s
SIG Sauer P320 Pistol Firing on Its Own, Owners Say
U.S. Continued to Back Cameroon Proxy Force Despite Abuses
States eye allowing concealed carry of guns without a permit
AK-47 History - C.J. Chivers The Gun Excerpt
How the AK-47 and AR-15 Evolved Into Rifles of Choice for Mass Shootings - The New York Times