Well, no family members in the house or not, chances are you'll break something or destroy your walls. All because you're aiming for them doesn't mean it'll hit them. I know my FA-MAS, which clocks a constant 260 (yes, only 260) doesn't just put a dent in the wall, it puts a decent sized hole in it. I'd hate to see what my AUG or one of the various GBBs would do.
Also, that law exists. Doesn't stop most people from plinking in the sanctity of their basements, but it's an actual bylaw and we have it here too.
Age verifier- Halifax region