What appears to be a sub-compact Stainless Kimber Ultra Raptor is seen used by Darling (Eiza González) as her personal sidearm. It is later seen used by Baby (Ansel Elgort). The Kimber is also featured on the film's poster.
SIG-Sauer P229R two-tone
What appears to be a SIG-Sauer P229R with a stainless steel slide is used by Buddy (Jon Hamm) in the gun dealer shootout scene. It can be identified as a SIG P229 by the short slide, by the grooves on the slide and the reflection on the metal trigger.
SIG-Sauer P228R
What appears to be a SIG-Sauer P228R is used by Buddy (Jon Hamm) for the second half of the film. Buddy appears to have an affinity for SIGs.
The Gunman with the MP5K also uses a Tan Heckler & Koch HK45 during the chase.
Smith & Wesson M&P
Officers of the Atlanta, Georgia Police Department are shown to carry Smith & Wesson M&Ps as their standard-issue sidearms. This is quite accurate, as, in reality, the Atlanta Police carry M&Ps.
M1911A1 variant
Inside the pistol cache on the bottom right is what appears to be some kind of 1911A1 variant with thin front and rear cocking serrations, three-hole trigger, rubber Pachmayr grips and (possibly?) a ring hammer. It is entirely possible that this is simply a Colt XSE or a similar variant with Pachmayr grips.
Walther P99
A first-generation Walther P99 is seen in the illegal weapons cache. It is never being seen fired and could just be simply a rubber prop.
Glock 26
A third-generation Glock 26 is seen in the illegal weapons cache. It is never being seen fired and could just be simply a rubber prop.
Submachine Guns
SIG-Sauer MPX
Dual SIG-Sauer MPX Pistols are wielded by Darling (Eiza González). The sound effects imply the MPXs firing in fully-automatic, despite obviously firing in semi-auto.
A gunman during the weapons deal shootout is seen firing an Ingram MAC-10.
Heckler & Koch MP7A1
On the left of the illegal gun cache are two Heckler & Koch MP7A1s. They are never being seen fired and could just be simply rubber props.
SIG SG-552
A SIG SG-552 "Commando" appears to be located behind the CAA Tactical RONI-G1 Glock conversion in the illegal weapons cache. It is not ever fired and could be a rubber prop.
CAA Tactical RONI-G1 Glock conversion kit
What is strikingly similar to a CAA Tactical RONI-G1 kit to put over a Glock 17 pistol is seen in the illegal weapons cache. It is entirely possible that this is what is seen here.
Assault Rifles
Custom AR-15
Buddy (Jon Hamm) is seen firing a custom AR-15 throughout the film. It is never seen closely enough to identify specifically, but it appears to have a 10.5" barrel, an aluminum free-floating railed handguard, a red-dot sight, a foregrip, Magpul furniture, a round trigger guard and what appears to be a 4-prong flash hider. Humorously, the firearm appears to fire in full-auto yet the sound effects seem to indicate semi-auto. This is the exact opposite error that Darling's MPX have. The AR is also seen on the film's poster.
AKMS
Two AKMS assault rifles are seen in the Butcher's illegal gun cache, one with wood furniture and one with aluminum rails. The one appears to be Polish by the wood furniture. Bats (Jamie Foxx) later acquires it and uses it during the gun deal shootout.
Colt Model 733
A Colt Model 733 "Commando" is seen at the bottom of the Butcher's illegal gun cache.
"The Butcher", the illegal gun salesman (played by Paul Williams in a cameo) offers up a weapons cache for sale. Some of the weapons seen in the cache includes some pistols, submachine guns, assault rifles and grenades.