Could be done a million times easier.
Right click on the first one you found.
Click find out what accesses this address.
Choose a function that is used all the time and substitute it with "mov [eax+00000020], 64".
Not actually eax+00000020 but where ever ammo is stored.
Complete the CE tutorial if you can't understand what i'm saying. You can do so much more if you know how to memory inject.
In sp, you play with a storyline. In multiplayer you are rushing and there is not a specific story. But I am not complaining about people who used this tool it was only a QUESTION.
and at least. I use a hack in MP for a long time, and it still works. just use hacks carfull