From the "Accelerate" patch notes:
The system for upgrading weapons has been modified. Players will now automatically receive weapon upgrades as they play a particular weapon, without having to spend XP on the upgrade (allowing you to save your XP for other items). A progress bar on the weapon’s menu page will provide information as to when the next automatic upgrade occurs. If you are impatient and have excess XP, an option is still provided to immediately master an item using XP. Note that previously purchased upgrades are still owned.
This affects primary weapons, secondary weapons, belt items, packs, armor, and maybe perks too (I don't have any yet so I can't confirm).
What does a player do to accumulate item xp? Is it as simple as including the item in a loadout and playing a match or do I have to use the item in some way?
At what rate is this xp accumulated? Can I do anything to influence that?
- Does holding/firing/damaging with a weapon matter?
- Does throwing/damaging with a grenade matter?
- Does skiing/jetting/getting damaged with an armor matter?
- Do activatable packs need to be active to get xp?
- Do passive packs need to be functioning to get xp? Health/energy regen packs don't do anything when you're full.