Why did you waste ammunition and put your neighbors at risk with a warning shot? If you are justified to shoot, you are justified to shoot center mass.

A bad guy knows he's a bad guy. He knows he isn't supposed to break and enter. Getting shot by a scared homeowner is part of the job description.

The police have a requirement to notify that they are police, "Stop or I'll shoot" and all that, but even they are responsible to account for every shot they fire and warning shots by definition don't hit the bad guy. Do police fire warning shots?

I don't think warning shots are required, desired or wise. Those are just stray rounds that need to stop somewhere and you better hope nobody -- specifically your neighbors -- gets hit by your warning shot. I like my neighbors, no way will I put them at risk with warning shots or firing through doors. Shotgun rounds/shot/balls that exit a body are moving much slower.

If put in your scenario with bad guys breaking in my door with the knowledge that I'm inside, my first shot will be center mass as soon as the door is out of the way. The second guy can listen for the shotgun racking in the round with his name on it. I'll probably be on the walkaround with the 9-1-1 operator until the shooting starts, the phone will fall where it falls.