There should be a checkbox or 2 when buying weapons/vehicles to auto upgrade to maximum with silver / upgrade orders if available (ofc that will ruin min-maxing with silver only 1-2 lvls then upg order final lvl but would be a nice feature to quickly get you going without having to diddle the weapons 20 fkin times before they are useable)
Right now, the only way to get max 3 stars automatically is: you set a weapon preset for the soldier class, and that weapon is already maxed out.
If you don’t have the weapon in your inventory and you repurchase it via the preset, the game will instantly upgrade it to full stars. Still, it’s a bit of a hassle.
As far as I know (I tested it) there is no such automatic upgrade.
Quick example: I equipped a fully upgraded Mosin M44 Rifle into the first engineer from my preset and had no more in reserve. I bought it via preset and I would have to upgrade the weapon by myself.
So where is your “automatic upgrade”? Are we playing different games?
Then I got it wrong. Maybe the interface where the system automatically assigns you the best weapons is the place where you can directly buy 3-star gear.