Years ago we had an old house here on the ranch. Before we tore it down, I wandered around the inside wearing my Civil Defense helmet and armed with a bagfull of buck & birdshot and my Ithaca pumpgun. I shot from this angle and that, thru the walls, floors, doors etc.

A charge of 00 would go through the drywall ceiling, Tamarack/Western Larch flooring of the upstairs room, stick in the roof planks but not go through the metal roofing. It would go through an inside wall and the next room {unless being stopped when hitting a stud}, but stop in the outside wall on the other side, except...

Some individual pellets would do interesting things. Maybe they rode the wake of others before them, I don't know, but sometimes a pellet would penetrate when it didn't make sense for it to do so.

I reckon I lost a little hearing but gained a little appreciation for the use of buckshot indoors.