Not theoretical at all. M1Abrams uses smooth bore ammo that is laser guided (you really think they can compute elevation, wind shear and moving lead on an independently moving target and all that stuff while jolting over the rough ground themselves at 60mph?)
An electronically controlled and stabilized laser locks on and then paints the enemy tank while the steerable smooth bore round homes in on it.
Have a smooth bore 50 cal rifle that fires a 50 round with a mobile nose tip that can "steer" the bullet to some degree, once again homing on a laser painted target point. Won't shoot around corners though, not unless it is a really really BIG corner .... it doesn't miss though.
Have artillery rounds that will do the same thing. Mortar rounds too. Have adaptation kits for old WWII design dumb bombs that makes them "smart bombs" using same sort of tech.
Have shoulder fired weapon that will shoot just past the wall the bad guys are crouched behind, then blow up the round 2 feet past the wall and shrapnel the hell out of whoever is behind it.
And that's just the stuff that Tom Clancy, Dale Brown and Modern Marvels (History Channel) has told us about -- then you got all the really neat new top secret stuff we haven't been told about yet.