When you equip a weapon there a HUD in the upper right corner of the screen who shows the weapon equipped, the magazine equipped on this weapon and how many bullets left. The problem is that always shows 100 bullets and this number don't drop.
The ammo still wastes as we shoot, only the message on the screen is shown wrong. I added a screenshot that shows the correctly number of ammo left and the wrong message on the screen. {F29051}