The AMC Auto Mag is seen in the 1st episode with Julian Crouse.
Derringer
Gilbert Ross uses a black derringer in the 12th episode.
Glock 17
The Glock 17 is the standard pistol used by officers under the Royal Cremoan Police's Royal Investigation Service.
Glock 19
The Glock 19 is used by Eric Toga, the head of the RCP's RIS. It's also used by Laica in the 12th episode.
Glock 26
The Glock 26 is seen with Mario in the 9th episode. He's suppose to be armed with the Glock 17.
Ruger Mk I / Mk II
A pistol is used by a Market Maker commando to execute Jaula Blanca medical staff in the 11th episode. It was seen very briefly, but the general shapes resembles either a Ruger Mk I or Ruger Mk II.
.22 Caliber Pistol
Izanami fires an unknown pistol at the 3rd episode. From the looks of it, it resembles the fictional .22 compact pistol used in Ghost in the Shell: Stand Alone Complex, which would make sense Production I.G. was in charge of the show's animation and production.
Revolvers
Colt Anaconda
What appears to be a Colt Anaconda is used in the 7th episode by the the twins.
Smith & Wesson Model 36
The Smith & Wesson Model 36 is seen with Keith Kazama Flick as his sidearm, only seen in the 5th episode.
Webley Mk VI
The Webley Mk VI appears to be used by Keith after he goes into hiding to avoid being caught by MM forces.
Submachine Guns
Heckler & Koch MP5 (Unknown)
The silhouette of a Heckler & Koch MP5 is seen in the 6th episode with Market Maker commandos.
Shotguns
Remington Model 31
The Remington Model 31 is used by Julian before he encounters Quinn in the 1st episode.
Remington Model 870
The Remington Model 870 is used briefly by Keith when Minatsuki attacks the Heian-ji the 7th episode.
Sniper Rifles
Barrett M82A1
A Barrett M82A1 is used by Takeru in the 8th episode to take out Keith's shack.
Grenades
M26 grenade
The M26 hand grenade is seen in the 3rd episode to slow down Koku pursuing Izanami.