Where and how to upgrade a weapon in Salty Springs?
Salty Springs won't be hard to locate since the town is named and is directly west of The Authority. However, we advise you to land nearby and then collect resources, as you will need them later. Once you have a large stock of wood, stone and metal, but also a weapon, go to the northernmost building in the city, red in color.
Inside it, in the garage more precisely, you will find a improvement workbench. You just have to interact with it to improve one of your weapons. The red house is precisely marked on the map above.
Note that to make your job easier and not force you to collect a lot of resources, we advise you to take an intermediate level weapon. This challenge can be achieved in a normal game or in a Team Rumble, the latter mode being preferred to save time.