I had the idea to combine the most hot ballistic weapon with the coolest weapons in the game... Gauss rifles, in fact. Despite the lack of damage, Light Gauss has nearly the same DPS as standard Gauss, a lower "charge up" time, which makes them quite viable at mid ranges. With ammo skills this mech can dish out around 1300 damage, so you will not run out of ammo that easily. Since the RAC5 will jam before reaching a critical heat level, you should skip at least half of the operation tree.