Jack Coughlin, a gunnery sergeant in the Marines, is the author of the new book Shooter: The Autobiography of the Top-Ranked Marine Sniper. He grew up in a wealthy Boston suburb and joined the Marines at age 19, spending the next 20 years behind the scope of a long-range rifle as a sniper. He has more than 60 confirmed kills, 38 of which took place during Operation Iraqi Freedom.