The benchmark is the amount of time it takes for a drone to explode between 400 and 200 yards under fire from these aircraft while at full gunsight zoom.
Offline take up your primary ride and perform the above task. If the plane goes boom with a 1-2sec burst then your convergence is good for this version of the game. The P51D is a good benchmark because how you set the 3 pairs of guns convergence correlates directly to a known weight of fire for 1sec in a general area between 200 to 400 yards.
Once you are in the MA, if at the same ranges with relatively easy angles shots you cannot destroy a con with a 1-2sec burst, something else is up. Possibly even the urban legend Internet gaming cryptid "Rubber Bullets"...........
Over the years with the P51D based on this benchmark I've had to set my convergence down to 250 with all 6 guns with some game patches or releases to have consistant kills in the MA. Other times combinations as varied as 650, 550, and 450 worked perfectly well. But, the next patch or release screws that pooch.
Some players right now may be facing the higher usage of the Internet during a series of world wide issues along with the long stormy winter here in the United States.