If you have trouble killing shptgun users, just sneak up behind, first for head and rest should be easy....
There are many players in this game that are good enough to not be snuck up on like that.
Yeah, good players also have to be nerfed.
The shotgun is balanced, more-or-less. When a goon can 1-hit kill you (and from quite far away if they're good with their pounce) and a mara can do it in 2 hits, does it seem OP that a shotgun takes 4 or 3 perfect shots respectively? The spread makes it so it takes at least twice that from farther off.
The only balancing I think would be remotely fair would be to decrease the damage per pellet to 6 or so, giving it 48 damage a shot. That way you can't take out a Tyrant in one magazine (lol, shotgun magazine) But then it takes 5 perfect shots to kill a goon, when a goon can still get you in one.