Haven't played against bots in a hot minute but pre-patch I ran the Shield/Pummeler (Polar Patriots warbond SMG)/Railgun. I'm actually going to play again in a bit with the same loadout to see how it holds up. The Pummeler is pretty kickass against both bots/bugs because of the stagger, ammo pool and one handed feature. Whenever I ran into Heavy Devastators (minigun or rocket ones) I'd just swap to the railgun and oneshot them with a hit to their leg(s). The biggest problem with this setup pre-patch was that the railgun didn't do dick to gunships so you were completely fucked if you ran into them, but now that you can kill them with 2 engine hits it's all good.