To get unlimited hand cannon ammo, get 60,000 points across all the stages with all five characters in "Resident Evil 4" on GameCube, including Wesker, Hunk, Ada, Krauser and Leon. Unlimited ammo is only available for a select number of weapons.
To get infinite ammo for the Rocket Launcher, complete the main game once in under three hours, using either the normal or hard settings. After the game, save your progress and restart the game. Beating the game on different difficulty settings also unlocks other options, including new costumes for some of the game's major characters and other rewards.