How can I know what is the maximum bullet capacity of a gun ? I would want shoot with a gun that has reached the maximum capacity. Like this, next time I find ammo for this gun, I will not waste them by not picking them.
Just use Last of Us Wiki to get info of maximum bullet capacity of a weapons. And according this forum and my personal memory, each magazin upgrade adds one more bullet to maximum capacity (or maybe a little bit more, maximum bullets of unupgraded weapon plus bullets in magazine).