I know, I'm the problem.

I'm sorry for the people I hurt in this.

No wait, you're the hawkish, blodthirsty military-trained killer who wants to kill a confused old man because his rifle is too short and he didn't get to penetrate anyone with it in a long time and that makes him feel inadequate!!!111

So what if the guy stayed away from windows? Do you shoot through the hostages standing in the windows to hit him? What if the bullet shatters the windows, sending millions of deadly splinters ricocheting through the room before it hits a gas pipe and the whole building explodes?