WTF sights in at 10 yards?......
Not everybody gets to shoot all the way out to 100, like you do.
For the OP, I never owned a boresighter, don't need one, just look down the bore like you did. Just don't limit yourself to a "target" that's inside the house.
I have a couple of things I use, just need a solid rest near a window.
The wife always worries about someone seeing me do that, but I just tell her I hope they do, then they'll keep their damn dogs out of the yard.