How to deal with enemies with full-body shields?
It turns out that in Borderlands 2 some enemies have shields, like Nomads and BUL Loaders. Some shields have minions on it, some have spikes, most are impervious to all damage and bad news in general. Sometimes those enemies will open themselves up to damage, but I can't figure out how to do so reliably and I'd rather not spend entire magazines of ammo trying to aim for the foot of these enemies.
I imagine commandos can play double trouble with their turrets, assassins can cloak and teleport around and whatnot, sirens can phaselock him for a while... but I'm a gunzerker. I regenerate health and ammo every once in a while and dual wield guns and that's it! I have to go through this the hard way... do I?
What's the trick here?
Elemental effects tend to take effect "around" the shield, so Damage Over Time can take effect, explosive rounds can cause some damage, and you can slag them. This is generally slow and will take lots of ammunition and time though. Grenades are a way to get explosive damage on them without swapping guns.
If you're a Siren you can simply Phaselock them and shoot their bodies. Otherwise try to move in and get around them. Alternately, stay way back and get a sniping headshot. The shields are the biggest problem at medium range; you really need to either get closer or get farther away. Also note if you're close, you can feint in close to them, at which point they'll slowly start a melee shield bash attack. You can get a second or so of free fire on their bodies while they do this.
You can also shoot through their shields, either by blasting off part of the metal (full metal shields) or by killing/freeing the midget from their shield. But the collision detection is extremely buggy around those holes, and most bullets don't seem to go through them right, so I avoid using this strategy.