Took a closer look at one of my Fujinon W's today, and it has the same "issue"-- if you look through the front lens with the shutter open, you can see the diaphragm opens to the diameter of the lens element at f/5.6. But the aperture lever has some further travel, allowing the blades to retract farther. The lens, though, is the limiting factor.
So on mine, f/5.6 is fully open for the lens, but not fully open for the shutter body.
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