The XM-32 Viper is a select-fire assault rifle designed and developed within the top secret location of the United States known as Area 51. It serves as the standard issued rifle given to the soldiers who serve at the secret location.
The XM-32 is one of the first weapons the player gets through the eyes of Bravo Team Biology Specialist Ethan Cole and can be used at anytime. The weapon features an advanced scope that isn't used, but helps narrow the shooter's eye. It also features an underslung flashlight similar to that of the M-11 Scorpion Pistol. It can be dual-wielded by the player, however reloading it causes the player to drop the second rifle entirely. The magazine of the weapon is a 30 round magazine chambering a 6.8mm Full Metal Jacket ammunition.
According to the Movie Firearm Database, the XM-32 best resembles the Heckler & Koch HK53 compact assault rifle, a variation of the Heckler & Koch HK33 chambered in the 5.56×45mm NATO.