To select the weapon you would like to use, pause the game. Then shoot off-screen or press C button. Cycle through the weapons. (Note: the cheat menu must be activated.)

Weapon Type Shots Reload
Automatic single-shot 15 Yes
Machine gun continuous burst 30 No
Magnum single-shot ? ?
Revolver single shot 6 Yes
Rifle single-shot 24 NO
Shotgun three-shot burst 6 Yes
The Special single-shot -- unlimited