As you know .357 mag. revolvers also shoot .38 spec. A revolver is also less likely to have function issues in my opinion.I agree with the #4 buckshot.....but disagree on the .357 mag. This round has perhaps the loudest and sharpest crack of nearly any handgun. The cylinder gap gives even higher decibel in a hallway. Perhaps a lower pressure 180...
Also, the OP never said his wife didn't want him to shoot in the house.
I do think his current set up is fine.