Firing pin is below the surface, inside the bolt head when it is cocked. A non issue IMHO. The ejector plunger shouldn't be an issue either. Drop the gauge or piece of brass in the chamber and close the bolt. Adjust the headspace and go from there. I don't bother to use gauges anymore. Leaves too much slop in the chamber. But, ever one of my rigs in a wildcat chamber so I couldn't fire factory ammo even if they made it. The less you move the brass from fired state, the better.