Gun sights for US fighters

[pandacat]

Hi just a few questions on gun sights.
1. Although corsair and wildcat-4 are using the same standard navy sights, only the inner ring on corsair's sight is visible. The outer ring is barely visible, obscured by the glass. To see the outer ring, one needs shift or tilt left or right. F4F-4's full gunsight is visible unless you move too far to either side. Any way to get the full sight out on corsair.

2. F4F-3's sight is different from the rest of the navy. It looks like a ring and dot sight on an army plane. I wonder if I can use the same ranging technique as in army's.

3. Also, is USAAF's sight a 70mil one? Meaning a zero wingtip to wingtip across the circle is 171 meters away. For FW190, it's 150 meters.

4.What deflection angle doesn't the ring on USAAF's sight represent? 20deg or 30deg.

5. The deflection angle on the navy sight is 20deg for outer ring and 10 for inner ring?