In clientshell you can change the weapon icons. The last time I saw these the offset was 0x6000 or so. And they were separated by 0x20 bytes each of them.
Those positions are read-only. You will notice it when you will change them. The ammo can be changed however the server checks for ammo and won't do any damage if you normally wouldn't have any ammo left in the current clip. The current weapon index won't change the weapon loaded at the screen. However you may notice that the weapon behavior changed to what you've set.