So normally for weapons I set up all logic in the weapon actor itself and keep the HUD class purely for visual representation. I also only update when necessary by linking the HUD update to the fire weapon action. Something like this
So that when the weapon fires it reduces it’s ammo and then maps the range and using a reference I have to the HUD passes in the already clamped value to be updated there.
I know your logic for the weapon is a little different but for addressing the initial problem I can tell you that this way works flawlessly to update the HUD and hopefully it’s enough to help you identify where the problem lies if it’s only the progress bar that’s not updating.