To my knowledge the guns aren't test shot for any zero. They are only test fired for function and eve that is done in a "machine" thing that's kind of like a drawer. The gun goes in, goes bang a couple of times, then comes out. I believe any "zero" the guns hold is just based on the tech specs of the gun and sights ... not really a "zero" for that gun.
This is opposed to say, a custom 1911, that is accuracy tested and adjusted as necessary.
Might not answer your question per se but beats around the bush.