Authorities recovered an “AR-style rifle” at the scene of the shooting, according to law enforcement officials. The gunman fired from a roof outside the rally, the officials said.

One study identified five principal factors that significantly affect shooting performance in elite air rifle shooters ... in motion or during a shooting stance. Intrinsic Motivation: The internal ...

Federal officials investigating the shooting said the AR rifle was “nothing special ... heat and the prone firing position ...

He grabbed three guns from the house -- a semi-automatic AR-15 assault rifle made by Bushmaster and ... Authorities say the first emergency call about the shooting came in at "approximately ...