I have the answer and yes the gun will go back to S&W. I was guessing when I said .050" excess headspace. I looked at the gap and being a machinist by trade rattled off .050". I didn't miss by too much for guessing by eye to the thousandths. It has .039" headspace on the go gauge and .025" on the no-go. The ammo fires fine in one of my Winchester 42's {the only 410's I own} and is made to SAAMI specs. Interesting that this gun uses an inertia firing pin so if you look at the protrusion with the hammer down it appears to be short of not coming thru the breech far enough. If you reach back and push in on the back of the firing pin it has plenty of protrusion. Anyone can make a mistake, and I am sure they will fix it. I know alot of guys complain, but I have personally had good luck with S&W customer service.