Body of Lies

The following guns were used in this movie:

Heckler & Koch G36

British SWAT team moves into position. H&K G36 rifles are clearly visible - 5.56mm

A British SWAT team moves into a building where a terrorist is making a bomb. They have RIS rails on the top of the receiver and have EOtech Holographic sights mounted and flashlights mounted to the side of the barrel.

Heckler & Koch MP5

In a high contrast shot from the Trailer, we can see H&K MP5s - 9mm

A British SWAT team are carrying A3 models with tactical flashlights.

Heckler & Koch G36K

Roger Ferris (Leonardo DiCaprio) fires a H&K G36K at pursuing terrorists - 5.56mm

Although it is apparent that the weapon used was a member of the G36 system, it is difficult to distinguish the exact variant. It is clearly not the Compact model(G36C), which is apparent by the shape of the rail. Judging by the barrel, it is most likely the G36K, where "K" stands for "kurtz", the German word for "short".
DiCaprio fires at a pursuing pickup truck in the desert.

FN MAG

Helicopter crews have FN-MAG 58 machine guns mounted as door gunners - 7.62x51mm

Seen mounted on the doors of helicopter gunships.

AK47

Terrorist carries an AK47 rifle when capturing Roger Ferris (Leonardo DiCaprio) - 7.62x39mm

Seen carried by terrorists.

RPG-7

Terrorist fires an RPG-7 at a helicopter. It looks like the rocket head is the V model or later variant.

Islamic terrorist uses it during the desert chase, trying to kill Agent Roger Ferris and then trying to down an attack helicopter. (Leonardo DiCaprio)

Glock 19

Ferris uses the Glock 19 in the desert as his sidearm - 9mm

Agent Roger Farris (Leonardo Dicaprio) uses this as his defense weapon in the desert.

Glock 17

Not confirmed at this time, but Agent Roger Farris (Leonardo Dicaprio) apparently uses a full sized Glock 17 during the gunfights in the city.

HK USP Compact

DiCaprio loads a HK USP Compact in his car.

Scorpion Vz-61

Farris uses this weapon to assasinate an Al-Qaeda cell double-agent in Baghdad in order to prevent any description of himself being given under duress.

Heckler and Koch MP5K

used by Hani's men to rescue farris.

M14

Used during the desert scene to cover Farris' entrance to the safehouse.