The N9 and N9 with rocket aid is a 101Mil ring. Or 100mph ring. The L3 was modified from a 50Mil ring to the N9 101Mil ring with the rocket\bomb aid cutouts for the P38L.
Comes from the measurement of a fighter traveling at 100mph right to left at 1000ft will travel 50Mil in 1\3 of a second. The relationship is to the time it takes the bullet to reach 1000ft. 1000-1200ft was considered the max effective range for the 50cal to still hold enough energy to effectively damage anything in air combat. The reticle cutout for the line projected is about a 6Mil width on the reflector plate. This could vary, like with the Mk8 series were slightly narrower. If you turned up\down the rheostat, the width of the line would vary also with the intensity of the light. Even sunlight would affect this.
The early Barr&Stroud MkII round glass gunsight, the glass was 3 inches. The L3 is not far off, and the British reticle had a 100mph ring. But, then who's unit of Mil is that based on. The British 100mph ring at 100 meters is 105Mil if you measure a 10.5m wingspan Fw190A.
So hop in a hurricane or a P38L. Put on zoom and increase until the sight glass is about a 1\8in short of 3 inches holding up a ruler. That will be real life. Kind of close ain't it.....
In our game I construct my reticle to Hitech's 2pixel = 1Mil. At which point the size of the glass the artist fits to the cockpit doesn't matter.
I will suspect you downloaded the latest historic pac to get the gunnery manuals. The answer to the N9 100mph or 101Mil ring was in the AAF fighter Pilot Gunnery 1943. That's why I gave you guys those manuals. By page 7 the reason for the Mil size was explained. The rest of the manual is the meat of how you use those 50Mil at 1000ft.
