Few addresses I found for zombies
Gun 1 Reserve Ammo: s2_mp64_ship.exe+A4AFE70
Gun 2 Reserve Ammo: s2_mp64_ship.exe+A4AFEC0
Gun 3 Reserve Ammo: s2_mp64_ship.exe+A4AFEAC
Gun "2" Reserve Ammo: s2_mp64_ship.exe+A4AFED4
Gun "2" Reserve Ammo: s2_mp64_ship.exe+A4AFEE8
Gun "2" Reserve Ammo: s2_mp64_ship.exe+A4AFEFC
Gun "2" Reserve Ammo: s2_mp64_ship.exe+A4AFF10
***Note: the Gun "2" is because after giving yourself various weapons, the ammo in magazine and reserve ammo pools get....weird. After giving a new weapon, there would be a whole new offset for that new weapon's ammo reserve. Probably because, depending on how you give yourself the weapon, you can start carrying 4-5 weapons (with one weapon that's weirdly glitched). The 4 that I listed there were the first 4 that show up if you give yourself a new weapon but if you keep giving new weapons, you'll eventually get a weapon whose reserve ammo is at a new address that isn't listed here.