On the US apc AAVP RAM, the HUD for aiming display the 50cal on the left and the grenade launcher on the rigth.
Main ammo is the grenade (left button of mouse), and the secondary ammo is 50cal (rigth button). It is not really a bug but not convenient.
Can you invert the primary/secondary ammo to make it more intuitive ?
Also need to change the ammo counter side
Test on Saarema.