Question about cheats for RE2

Hi, I'm new here. I downloaded Resident Evil 2, beaten it with Leon and Claire, now I want to start the game with whatever weapons I want, like the Magnum. I followed the instructions for adding the cheats, and tried them out, but they don't seem to work.

Please help me!

FYI-This is how I did it:

The region of the game and cheats are North American, and the cheats are Gameshark. I don't know if it is a good64 checked ROM at all, sadly. Could you tell me how, then I could answer that question.