Quote: "The real problem with having a gun in the middle of a shield is, you can't cover an exposed angle while firing in a different direction."
Well then, make the gun seperate from the sheild... oh.
I was gonna post about my idea for a large cylindrical sheild with a gun on a track that could move around the full 360 degrees, but then I realised I was basically describing a small tank.

Still, I think there is potential for this sheilds + guns combo - for instance, if you're firing a gun you're usually aiming at your enemies, why not a small peice on the to of the gun to protect the head and face, for example? But then I suppose a helmet is both easier and more effective :/