Help with resident evil 5 cheats?

the cheat says if u max out the up grades of a weapon you get unlimited ammo for that weapon my pistol and machine gun still go empty and i cant reload them, any ideas why

P.S. they the basic pistol and SMG.Help with resident evil 5 cheats?
i believe you have to finish the game and then from the special features you have to buy the infinte weapon from the list and then when you start a game there will be an option for unlimited ammo. that should work.