The gunman who massacred 13 people at a country music bar ...

Ian Long, 28, the gunman who opened fire

 on Borderline Bar and Grill 

in Thousand Oaks, California.

Tattooed trenchcoat-wearing decorated ex-Marine, 28, is identified as gunman who massacred twelve people during student night at country bar: Suspect killed himself after hurling smoke grenades onto dance floor and slaying cop in California ...

Long had modified his legally purchased handgun so that it could hold more rounds.

'The handgun is designed to hold 10 rounds and one in the chamber. This weapon did have an extended magazine on it. - Source