New Dominion Tank Police is a 6 part OVA based on the 1985 manga series Dominion: Tank Police written by Masamune Shirow (creator of Ghost in the Shell, Black Magic M-66 and Appleseed).
The following firearms are used in the anime OVA New Dominion Tank Police:
Brenten uses a custom 8 inch, stainless steel Colt Python revolver known as "The Castigator". It boast a wide range of custom features, including custom frame contours, texturing on the front of the triggerguard, a custom barrel weight and compensator. and a ring hammer. Oddly, the revolver is drawn as being built from a Smith & Wesson Model 66 during the opening credits, as denoted by the S&W-style cylinder release.
The criminal in the first episode uses an unidentified handgun to hold a restaurant owner hostage.
A M1911-esque pistol and the grip of a revolver can be seen in the bag of confiscated weapons in the police office.
(Doesn't the front of the slide on the pistol look more like a custom Baretta?)
This reoccurring design is first seen in Act 1, where it is outfitted with a sound suppressor, and then is featured more prominently in Act 4. The design draws heavily from the S&W 39 series pistols.
Members of the Newport Police Department are armed with an unidentified type of revolver.
Charon, Leona's old partner, uses this handgun during a flashback sequence in Act 2.
Submachine Guns
MAC-11
Leona Ozaki's weapon of choice is a MAC-11 submachine gun chambered for .380 ACP/9mm Short. She occasionally uses non-lethal "stun rounds" (likely rubber bullets) to subdue criminals. Another MAC-11 is seen during Act 2 in the hands of a criminal during a flashback sequence.
Steyr TMP
A Steyr TMP can be seen among the confiscated weapons in the first episode.
Heckler & Koch MP5K
One of he criminals in Act 1 uses a H&K MP5K with a ridiculously large sound suppressor. Another MP5K in the same configuration is seen in Act 4. A single unmodified MP5K is seen in Act 5 in the hands of one of the Mayor's bodyguards.
Rifles
AK-47
Several AK-47 rifles can be seen throughout the series. At least one of these rifles belongs to the Tank Police Squad. More AK-47s can be seen in Act 5 in the hands of various criminals during a crime wave.
AKMS
A discarded AKMS can be seen at a crime scene in Act 5.
Seburo MN-23
Nam is seen cleaning several Seburo MN-23 rifles. Another MN-23 makes a brief appearance in Act 4 in the hands of a criminal.
Bullpup Rifle
During Act 3, several Newport City Police Officers are seen using a fictitious bullpup rifle. The weapons aesthetic design seems to be primarily inspired by the Mossberg Bullpup shotgun.
Heckler & Koch HK33A3
A single police officer can be seen with a Heckler & Koch HK33A3 with a 40 round magazine in Act 6.
Security Rifle
The MPs at the air base in Act 6 use a fictional assault rifle.
Shotguns
Full-Auto Shotgun
One of he criminals in the first episode uses this fictional fully automatic shotgun. The weapon is fed from a drum magazine and has a heat shield covering the barrel.