Primaries level up from use, unlocking customization options in different slots. Slot availability varies by gun. It looks like all weapons have skins (great for the fashion game). The slots I've found so far include:
sights (different sights to taste, or trade off zoom <> ergonomics)
muzzle (recoil patterns mostly)
grip (recoil <> ergonomics/laser/flashlight)
magazine (capacity <> ergonomics/reload speed)
Looks fun! I kinda wish we could slot a bayonet but I can see why they would keep that exclusive
How does the ergonomic stat affect the weapon?
IIRC that's how snappy the aiming is - how long it takes for the barrel of the gun to catch up with where the cursor is aimed. (The circle reticule that follows the cursor)
Oh damn! If only I could upgrade support weapons. I want ergonomics on hmg and a better scope on railgun
I really want armor perks and armor cosmetics separated
Also things like reinforced scout strider kills should count as scout strider kills!