I'm not familiar with the book. Here is a piece from Wikipedia on the hardware.
http://en.wikipedia.org/wiki/Shooter_(2007_film)Shooter depicts a number of sniper tactics, thanks to the guidance of former U.S. Marine scout sniper Patrick Garrity, who trained Mark Wahlberg for the film. Garrity taught Wahlberg to shoot both left and right-handed (the actor is left-handed), as he had to switch shooting posture throughout the movie, due to Swagger's sustained injuries. He was also trained to adjust a weapon's scope, judge effects of wind on a shot, do rapid bolt manipulation and develop special breathing skills. His training included extreme distance shooting (up to 1,100 yards), and the use of camouflage ghillie suits. Fuqua appointed Garrity as the film's military technical advisor.
In the special features of the DVD, Garrity is interviewed pointing out that the shot fired in the assassination would not have hit the archbishop straight on, as in the film. When a round is fired it will fall from 30–40 feet depending on the distance of the shot. To compensate, the round is fired at an arc calibrated by how far the round is going to fall, the distance of the shot, temperature, humidity, wind and the curvature of the earth. In his interview Garrity said "At 1,800 yards, because of the hydrostatic shock that follows a large caliber, high velocity round such as the .408 Chey Tac (which is used in the shot), the target would literally be peeled apart and limbs would be flying 200 feet away". The exit wound on the archbishop's head would have been too extreme to show in movie theaters. Instead, the movie depicts a much less graphic representation of the assassination.
Throughout the film, Swagger uses an array of sniper weapons, among which are the USMC M40A3, the CheyTac Intervention, and the Barrett M82 sniper rifles. Donnie Fenn used an M4A1 with a Cobray 37mm Launcher (commonly used by TV and movie armorers as a stand-in for the M203 grenade launcher) and M68 Close Combat Optic in the African opening sequences. A pair of Remington 700Ps were bought by Swagger and Memphis while on the run. Other weapons used by Swagger include a Beretta M9 and a commandeered M4A1 with an Aimpoint Sight, in the fight against the 24 mercenaries and a Colt M1911-A1 and a suppressed M4A1 in the final scene. Fenn's old .22 rifle that Swagger used on the lake scene is a Cooey model 60.
Also appearing in the film is a Precision Remotes Telepresent Rapid-Aiming Platform (TRAP), a remotely operated weapon platform that accepts a standard rifle. Precision Remotes' website appears in the film, and the company is credited in the closing credits.