I think there should be an option to deactivate the ammo counter in the HUD!
Instead players would have to count their shots or visually inspect their magazines to determine their ammo count.
The basic suggestion is just removing the text displaying how much ammunition remains in your current magazine from the HUD.
Instead players would have to count their shots and visually inspect their magazine to determine their ammo remaining. An example of how this would be done is that holding a key would temporarily unload the magazine from the weapon and hold it in the player’s vision allowing him to determine how much ammo remains in the magazine or displaying some visual element such as an exact number or inexact bar once this is done to aid in quickly being able to determining the approximate amount at a glance.
As a suggestion holding “R” could temporarily unload your magazine and have you inspect it while the key is pressed but since ArmA currently doesn’t support binding holding a letter to a command it could be just about any command really unless this kind of support is added. Other examples could be double-tapping R (currently also does not work well as this reloads the weapon) or Ctrl+R. It should naturally also be able to be toggled using another keybind should players wish so.
It could be taken even further by also removing the numbers indicating how many spare magazines and grenades players have, possibly only beyond their first one so players would always know if they have spares and just not how many, in which case players would have to check their gear in order to determine exact amounts. And finally the HUD simplification could go even further by even removing the weapon name, ammo name, firing mode, zeroing distance and grenade type by having these only be visible in the gear menu, directly on the weapon or in the most important case of grenades perhaps by your character briefly holding up the grenade to his face each time you toggle grenade types or by a minimalist visual indicator. Something similar.
Note that this should be an option and not mandatory! It could be toggled just like third-person view and many other options though if player support for this being mandatory on Elite difficulty I would think that sounds most appropriate.