We could have the anti-shipping version that I/ZG 1 used. It was moved into the anti-bomber role with the FuG 200 "Hohentwiel" radar removed. The A1\U4(BK5) and B2\U1(MK103) Zerstörer both had the ZFR4 telescope gunsight installed for aiming the primary long range weapon outside of bomber defensive fire range. Both of these versions supported additional forward firing pairs of 13mm and 20mm.
Antishipping Zerstörergeschwader
Me 410-B6 2-13mm, 2-20mm, 2-MK103, and FuG 200 "Hohentwiel" radar.
Something as large as a surface vessel would be the kind of target that the differences in ballistics would be acceptable at about 600m since you have such a large area of very slow moving target to shower rounds upon. But, as you saw in the offline target screen captures, the 20mm is not an acceptable long range weapon slaved to the MK103 past 650 while the MK103 can hit bombers from 1000 with a high rate of fire.
Sitting at 1000 behind a B17 is opening things up to a few random .50 cals reaching you. Still, if you do your home work offline and build your gunsight from testing against the target. You can become pretty accurate from 1000 with the MK103. I just hate to see players wasting half their 20mm while sniping bombers from 1000 yards in the game when an historical sollution exists within the selector switch.
Scherf,
The ZFR4 gunsight was a Revi16 body with a telescope incorporated into it just below the reticle projector lense. The pilot looked through the telescope which had it's own reticle to aim the MK103 or BK5. In the game you would simple use full zoom.
Zielfernrohre ZFR4A Gunsight
Reticle Image