When deciding to pick up ammo I always glance to the lower left to see how the team is doing on ammo, and seeing as how our max ammo can change for every single gun, and it only shows what is loaded+how much reserve you have, I don’t memorize my max ammo.
Adding the colored ammo indicator icon next to the player’s name as well will help speed up the decision-making process at a glance since good teammates will be looking there anyways.