Your idea of a nerf is too extreme. The shipka rate of fire is too high for any shotgun. Maybe, just maybe someone should fix the respawn bug associated with shotguns. If its such a big deal, complain about that getting fixed.

Shotguns should take you out in a number of close up hits, but not all at once. Just nerf the ROF, fix the respawn issue with shotguns and call it a day.

I think that idea of decreasing the damage when the bullets get out of a certain range might help for all shotguns, as others have said. Idk if I was against it, but it makes complete sense.