I explored Gunz.exe a bit more and I found out how to properly do it.
Code:
int GetAmmo()
{
int Ammo;
__asm
{
Call ZMyCharacter
LEA ECX,DWORD PTR DS:[EAX+0x38]
MOV EAX,GetSelectedWeaponAddr
CALL EAX
LEA EAX,DWORD PTR DS:[EAX+0x3C]
MOV EAX,DWORD PTR DS:[EAX]
MOV Ammo,EAX
}
return Ammo;
}
This code successfully returns the amount of ammo in my current weapon.
HitatchiHex, thanks for pointing me in the right direction.