Many years ago,i was cutting a chamber for a 270 Durham Magnum. Using a Commerical FN action. All measurements were perfect. When i buttoned up the barrel to the reciever,and using s stripped bolt to check the headspace,the "GO" gauge would let the handle of the bolt not travel all the way down. And the "NO GO" gauge would let the bolt travel all the way down to the reciever. This is jus opposite of what it should have been.taking the barrel off and taking measurements again,all was fine. Again,checking with my new headspace gauges, repeated the same. Finally after scratching my head,i measured the gauges,now these were made by a top notch company,found that the gauges had been marked opposite at the factory. So, never assume anything when problems arise! van.

Yup, it happened to me only not in that particular way. I was doing an Ackley improved chamber for which the standard go gauge is used as the no go. Well, I had the AI go gauge and could not close on it, but the standard go did. Sent them both back and got a completely new set for both of them.