look at this :

The claws2 needlers is correctly set up

This is a claws2 - NEEDLERS arena only, with no ammo changes allowed, only needlers !

Look at my weapon, my ammo, and the ammo / weapon pick up

Then I tried with all multi ammo weapons. I have noticed the same prolem with the grenade launcher (I tried with each kind of GL ammo of course)

As you can see, all is correctly working, but the first person view doesnt show the right ammo.
This problem occurs only with claws2 needlers and firemines, and with grenade launcher napalm, poison and disruptors.
I have tested also the mug ice, the crossbow poison, explosives, flame, and the sniper rifle RPB too, but all of them work fine.