I got lucky a few months back and got a Tediore Brisk Plasma Caster from the golden chest in Sanctuary. Holds 55 rounds, pretty damn accurate, not too shabby for power (6358). The only problem that I can see with it is that it's damn near impossible for me to find something to trump this. Also, it chews through ammo faster than I can gather, so it costs me a fortune in ammo resupply.
GT: pyromite; lvl 50 legendary commando in BL2 kicking names and taking @$$
I have complete sets lvl 50 plasma casters and the E-Blasters I have any incentive to try all of them to figure out any difference between each 1 though lol. If you guys have Tiny Tina's Cobra I'll glady dupe trade complete sets of plasma casters or E-Blasters for it. If you have variants of cobras I'll dupe both and acouple of other stuff you might be looking for.