I'm overhauling my irrigation system and I just bought some new Hunter
4" Pro-Spray bodies with green PDC-12A nozzles (stands for Precision
Distribution Control, 12' radius/distance). I have installed the bodies
and flushed them, and started putting in the nozzles. The nozzle is
supposed to be adjustable from 0 (zero) to 360 degrees. But when I look
at them, I'm confused: they appear to adjust for more than 360. Pictures show it better.

Here is the nozzle (I colored the raised dot with a red Sharpie so I could see it more easily when installing and adjusting):

Here it is, almost fully closed (zero degrees):

Here it is after opening one full turn (360 degrees):

But that is not as far as it can open! It can turn open another approximately 270 degrees. Here it is, all the way open:

Here I've repositioned it so that you can see both sides of the "stops":

So does this spray head open more than 360? If I want to use it for 180
degrees, how do I do it properly? For the one that is already
installed, I'm not seeming to get a lot of spray out if it. (By the
way, not to lead the discussion astray, but I did not ask for these
nozzles from my irrigation supplier. They talked me into them saying
they were a lot better than a few years ago and don't tend to "walk
open" over time any more. I'm aware that a lot of people don't like
them and they tend to clog more easily. I may just take them back and
ask for the fixed spray nozzles I wanted in the first place.)

Thanks in advance for the help!
Carol