From Internet Movie Firearms Database - Guns in Movies, TV and Video Games
The following weapons were used in the OVA Exodus!:
Smith & Wesson Model 29
The Smith & Wesson Model 29 is used in the OVA by a parody version of Dirty Harry. It's later used by Aya to clear a path to the Tokyo Bay Aqua-Line, which was blocked by anti-riot officers.