I still think individual weapons skills is a good idea.
Same here, but i have some more ideas for weapons in my head, with an eye on realism;Firearms suggestions
Most medium-long range weapons and some pistols
have adjustable iron sights, such as the AK and its variants
, that need to be re-adjusted when aiming from enemies at short ranges to enemies that are 900 yards away from you, perhaps this could be done in-game?
-Correct ammo system
This one's simple, if you come across an AR15 with 5,56 20/30rd STANAG magazines you can't use it's ammo to load your e.g. FN SCAR-H or AKM.
If you come across AR15 magazines but you´re carrying a Steyr AUG (any variant) you'll have to take only the bullets and load 'm into AUG magazines later.
So if you have a 120 5.56x45 bullets but only 3 AUG magazines, you can only use 90 of those bullets.
-Perhaps a cleaning system?
Weapons need to stay cleaned, or they'll jam (more often).
Perhaps i'll add some more ideas in a not-too-distant future!