I would also suggest a 12 gauge due to the commonality of such and you just might not need to discuss the issues with the cops should firing be necessary.
I would suggest a couple sandbags on the floor by the front door/window. First round or 2 should be directed into that. Unwanted guests should find another place to go immediately after and save you the headache of dealing with body disposal.
And if not, you have round 3-8 to continue to try to change their mind on on where to shop.
If 3 or 4 were were necessary, I would suggest skip fire. One or 3 hit in the lower legs would surely convince the rest to go away and certainly reduce follow up headaches for you.
If more than 4 were necessary, CoM, until empty, proper target variance, drop that weapon and pick up the modern sporting rifle right next to you and be ready to continue firing as the situation requires. At that point judicious marksmanship would be necessary. Spare magazines very close and easily accessible.
Nemo