Think dispersion in the case of wing guns. Nose, hood, and engine mounted were a pure case for being able to hit what you shoot at as a marksman.
I'm not going to insert pages from the AAF Armorers fighter gun harmonizing manual. Below are the convergences setteled on in general by 1945.
These convergences have 3 adjustable components where we have only the "one" Hitech gives us. The horizontal convergence related to the LoS of the gunsight. The real adjustments were first the horizontal and vertical of each gun to achive the crossing point along with a maximised or concentrated dispersion cloud at an IP point to which last the gunsight's LoS was centered relative to the AoA at 250-355ia. Most of us would make a mess of our gunnery if we could control all three parts manualy in the hanger. You can do exactly that by erasing the center dot on your gunsight and putting in a new one 34 pixels\17 Mil below center. I have a ghost line there on mine.
With the AAF there was an expected 4Mil cone of dispersion out to the effective distance of the round from each gun. This is why you see dispersion circles offline against the target that get larger in diameter with distance. 4Mil at 50yds is much smaller than 4Mil at 500yds even if the diameter of the black blob looks the same from your gunsight's perspective. Thats why longer shots are not always effective without holding down on the trigger for awhile. The same principel as with shotgun BB's when shooting at long range.
Our game vertical is tied to the primary gun so it's gunsight is centered at that horizontal crossing point. Some hood mounted guns need to be set 25 to 75 short of the primary guns to pattern them at the primary guns centered convergence point. One of the reasons for the offline target on auto level.
Most WW2 fighter pilots were good at estimating range using their Mil calibrated rings. Rule of thumb was to keep flying until the target fills your ring or more than half of it. Lead was the real problem even in low E shooting. Thus the advent of the Gyroscopic active gunsights and previous to that comic book style gunnery manuals like "Bag the Hun" and "Schiessfibel". It's good to know the time to target of your rounds 200-400yds and how far something travels at 250-300mph in that time. Then you will know how many 100Mil rings to hold over when you shoot. Sound simple yes?? Thats why the K14 gyroscopic gunsight was invented.
The AAF harmonized in feet not yards and 2000ft\666yds was considered the max effective. Bore sighting distances were at 1000 inches or 500 feet using ballistics tables and "similar triangles formula" to determin Mil angle and or inches difference from the center of the aircraft to the extended bore line. In each of these aircraft's extended maintenance manuals you will find specific instructions for bore sighting\harmonizing the guns along with how to service and adjust the center of the gunsight pipper to your bore sighting. Reminds me of when you had to adjust your head light patterns on your car.
Interesting thing about all of the AAF harmonization patterns just like in our game. The primary's horizontal crossing point, gunsight line, and highest point in the ballistics arch is the sweet spot. And then you have the dispersion cone of random flyers surrounding that.
P47
Guns Conv at--- Feet --- Yards
1 - 1 ------------1000---- 333
2,3 --------------1200---- 400
4 - 4 ------------1500---- 500
P47
Guns Conv at--- Feet --- Yards
1 - 1 ------------1075---- 358
2 - 2 ------------1075---- 358
3 - 3 ------------1075---- 358
4 - 4 ------------1075---- 358
P38
Guns Conv at--- Feet --- Yards
right ------------2000---- 666
right ------------2000---- 666
left --------------2000---- 666
left --------------2000---- 666
20mm-----------2000---- 666
P39
Guns Conv at--- Feet --- Yards
right W-----------900---- 300
left W-------------900---- 300
right hood-------2000---- 666
left hood---------2000---- 666
37mm-----------0 datum line <--was fired alone. Mostly for ground and shipping attack.
P40
Guns Conv at--- Feet --- Yards
1 - 1 ------------1000---- 333
2 - 2 ------------1100---- 366
3 - 3 ------------1200---- 400
P51B
Guns Conv at--- Feet --- Yards
1 - 1 ------------1000---- 333
2 - 2 ------------1000---- 333
P51D
Guns Conv at--- Feet --- Yards
1 - 1 ------------1100---- 366
2 - 2 ------------1100---- 366
3 - 3 ------------1100---- 366
