Press the ENTER key then enter one of the following cheats
dolemite-Soldiers are invincible
paul haney sees all-Show enemy soldiers
toggle bottombar-Switch bottom display
set_campaign-Select Campaign (See Below)
Add one of these to the set_campaign cheat above
Host a new Multiplayer game. On the Game Settings, one of the menus let you set unlimited ammo. Start the game, then quit it. Load an old game or start a new one and you will have unlimited ammo. You can do this every time you start a new game.