I'm also not expecting individual calibers, since damage modifiers (armor piercing, physical vs chemical vs fire ... as seen by the armor/protective types shown on gear) seem to be based on the weapon, not it's ammunition...
Yes. The gun nut in me hates unlimited mags. The gamer in me is SUPER GRATEFUL. Carrying 10 30 rnd mags around, taking up inventory space, urgh.
Well, this is late, so not really a suggestion at this stage, but just a discussion for the future.
Why do games focus on guns instead of ammo? Truly, I think a much better way of creating good (especially physical) gun mechanics is to create ammo that does a base damage, damage type (AP, hollow point, incendiary, EMP...whatever), and then develop delivery packages for that ammo type. Sort of...like guns...if I'm understanding how modern firearms are developed.
So, I'll pick the type of damage I want to do (up-front stopping power, elemental, non-lethal, etc.) then choose a weapon that handles that damage the way I want for my character or the situation at hand (precision, sustained fire, area saturation, etc.) Thus, the "gun" doesn't do any additional damage, it simply affects things like rate of fire, accuracy over range, how quickly I can hoist the weapon to sight targets, the amount of recoil I have to deal with, how likely the weapon is to overheat and jam, etc.
"Skills" and "Abilities" then manage the secondary concerns. Training with pistols mitigates the spread of bullets when fired quickly. Training in rifles means I can snap the sights up more quickly and maybe auto-drop-and-switch to a pistol if I run out of ammo. Training in heavy weapons lets me ready, reload, and clear jams much more efficiently. However, nothing affects the "damage" I cause except switching ammunition types.
And that creates some fun, as Sard mentions, with managing inventory and bringing what I know I'll need to get the job done "my (character's) way". I think that's easier to balance and more immersive than, "This pistol does +20 more DPS than that one. Because it's blue, not green."