Well, that was kind of the gist of the shotgun-Gauss hybrid. The idea I had in my mind, and your imagination may differ, is that it would be abundle of needles wrapped by some material that broke away, thus letting the individual projectiles flare out or separate during flight. I imagined that there might be a similar spread or area effect that the current shotgun has, but with the penetration of a Gauss based weapon.
It was one of my minor gripes with the basic CT combat system as a whole. As functional as it was and is, it didn't allow for too much wiggle room in terms of variant effects. What we're discussing here is an example, but so is the JTAS article on Archaic weapons, where they're essentially all 2D or mostly 3D in damage. So, I don't know.
Please tweak, alter or propose your own version of what I've put down here.