You ever go offline, enable the LCS green cross, and fly across the drone circle repeatedly for an hour to try and understand the lead and trajectory for the MK108? Grizz was right about setting the convergence to 350. It averages the flattest to 400yds.
Time to Target in seconds MK108.
---Target----100---200---300---400---500---600--yards
---500m\s---.20---.40----.60----.80---1.0---1.2--seconds
Combat Speeds 90 degree left<--->right Travel in Yards.
--Time----.10--.20--.30---.40--.50--.60--.70--.80---.90---1.0--1.5--seconds
250mph---11---22---33---45---56---67---78---89---100--112--168--yards\sec
300mph---14---29---43---58---73---87--102--116--131--146--219
350mph---17---34---51---68---85--102--119--136--153--171--256
400mph---19---39---58---78---97--117--136--156--175--195--292
Revi 100Mil Ring at Range
100mil at 100yds = 8.3yds
100mil at 200yds = 19 yds
100mil at 300yds = 30 yds
100mil at 400yds = 40 yds
100mil at 600yds = 60 yds
At 200yds.
Target traveling 300mph left to right covers 58yds.
30mm takes .40sec to travel 200yds.
58\19=3.05.
From the center of your gunsight ring hold over by 3-100Mil rings lead.
+OOO

This is why K4 aces in the game talk about aiming with the windscreen vertical bars when calculating lead. When you dive on a B17 you aim in bomber lengths ahead of it. B17 is 25yds long. Our B17's can fly at about 300mph. Shooting from 600yds back the B17 will have traveled 200yds in 1.2sec. So 8 B17 lengths ahead or 3.3 Revi rings. Offline using the LCS sight makes that look outrageous as your aim point. I'm giving this as an illustration of how much more lead you have to account for with a 500m\sec slow round. Not as bomber killing instructions for those who jump on these things as bad tactics.