Having just come from his location also, I have to side with my pals
In all honesty, I think that considering this is at best problematic, and it would simplify your life lots if you just used live ammo. What you do in the end is up to you, but remember that the BG may not have blanks and if he is shooting in your direction he may be shooting toward your family also. It would be best to simply shoot, tase, spray or otherwise disable/disorient him. Blanks will **** him off, and then he will feel the need to shoot back. Rather than a last resort or intimidation tool, his gun has become a defense weapon in his mind also.
There is just lots to consider doing something like this. take time to weigh the matter carefully before making a decision.