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Ray King (J.K. Simmons) is seen carrying what appears to be SIG-Sauer P229 in flashbacks to the Gambino massacre.
Glock 17
Brax (Jon Bernthal) along with some of his operatives are seen with the Glock 17. Christian "Chris" Wolff (Ben Affleck) also uses one at one point.
Heckler & Koch HK45
What appears to be a Heckler & Koch HK45 fitted with a suppressor is seen in the hands of Brax (Jon Bernthal). The pistol is also used by one of his operatives. Although this pistol has a threaded barrel it is not an HK45T model as the sights do not appear to be the ledge type tritium offerings that come with the HK45T.
Para-Ordnance Black Ops 1911 14.45
During the course of the film Wolff uses a Para-Ordnance Black Ops 1911 fitted with a threaded barrel, magazine well, a Surefire X300 weaponlight, and a SilencerCo Osprey suppressor. This is the 14.45 variant with a 14rd doublestack magazine.
Rifles
Heckler & Koch HK416
Wolff fires what appears to be a Heckler & Koch HK416 fitted with a foregrip, light, suppressor and Leupold HAMR/Delta point optic sight during the final shootout.
Remington 700PSS
Some operatives are seen armed with what appears to be a Remington 700PSS while guarding a home.
Barrett M82A1M
Wolff is also seen firing a Barrett M82A1M, first to snipe cantelope from a mile away, and later in two separate fights.
Machine Guns
GE M134 Minigun
A GE M134 Minigun is discovered by FBI agents in Christian's house, mounted to cover the front yard.
Other
Weapons Cache
Wolff keeps a hidden cache of weapons inside a mobile trailer.
Special
Actor Ben Affleck underwent firearms training prior to taking on the role in the film.