The only weapons i have recognised in this movie are is the Browning Buckmark pistol, .44 Automag, and possibly a 9mm Goncz carbine. The rest are pump-action shotguns, .50calibre machine guns, and the most noted weapon that Rambu(Peter O'Brian) uses that has interchangeable barrels that enable its purposes. Smoke can be seen coming out of cooling vents saying it could be some blank firer, and at one point when Mr White(Craig Gavin) is weilding it is turning some switch.
Below is the layout of the "Rambu Gun":
