I have no idea but the consensus I come up with from a quick google search; was an unofficial, anywhere from 25yds to not at all. One guy said they just center them up. Another said his was not centered, was too far to the right and after he centered it it was dead on.
My 22C was good out to 25 yards right out the box. I was able to put 30 rounds into a paper plate at that distance but the front sight (for me anyways) completely covers most all of my targets anything past 15 yards (I generally shoot at paper plate size targets).
My G 21 Gen 4 was dead on at 25 yards right out of the box. I took a rest on a milk crate with a folded up jacket, and aimed at 12 o'clock in the 10 ring, thinking it would shoot low. I hit high. Then I held at 6 o'clock in the ten ring for a few shots, which hit low. When I finally decided to quit putzing around, and aimed at the bull, that's where it hit. Gee go figure.
I kept the target to remind myself to not over think things too much. Here it is.