At hallway distances, a load of #4 birdshot is very similar to a solid projectile. Not much spread but a whole lot of damage.IIRC, way back approx 13 years ago, someone on here also mentioned having your first two fires to be birdshot, in case you needed a deterrent before the whammy shells were fired. Would love to hear some input on that, since it may or may not be something I still do...
I'd offer to tell those that want to differ to take a sheet of newspaper out and shoot it at 15'. Even with a cylinder choke and spreader wads.
You can let us know I'm right after your done.