Hitech left them at the AH2 centering for each gun.
20mm - 200
40mm - 400
The 20mm should be centered to the rear peep at 750 while the 40mm to 1000, then you adjust your drop and lead accordingly. Most people are missing in those guns because the rear peeps are centered too close. Come to think about it, I should have centered the wirbel\osti reticles at about 1000 instead of the center color mask for the gunsight reflector plate that centers the rounds about 200-400. I need to remind myself to test a version of that. And the green LCD needs to be calibrated, it's less accurate in AH3 than it was in AH2 past about 600yds. Unless that has ever been it's effective range.
But, very few people really use these guns if they never have to.