2 extra turns would've cut clean through the tube, they ain't that thick, & 2 turns of a 1.25mm thread is almost .100". Most likely the the thread/barrel of the NGK engaged the threads all the way to the chamber surface, cleaning the carbon off on their way through.
Sounds petty. I replaced my spark plug tube gaskets which negated the gap problem. I threw the napa box in the recycler. I can retrive it. The gaskets can easily be made from flat cork as well.
