Me410A-1/U1...
"At the beginning of the war our tanks could only open fire from a distance of 800 yards if they wanted to be sure of the results, while our latest types were in a position to combat enemy tanks from a distance of 3000 yards. The Jagdwaffe alone had not developed along these lines. They still had to close in to 400 yards before they could use their weapons effectively.
From this consideration arose the order for fighters and destroyers to use a large-caliber long-distance cannon against the American bomber formations. The result was as follows: an Me-410 destroyer, equipped with [the] armored-car cannon KWK 5, weighing 2000 pounds (!), was reconstructed as an automatic weapon with a magazine holding about 15 shells, [with] a rate of fire [of] about one shot per second. It was possible to fly with this monster sticking 3 yards out in front; firing was possible, too, although the cannon jammed hopelessly after about five shots. One could even hit something, not at 1000 or 3000 yards' distance, but at the most from 400 yards! Beyond that all chances of a hit were spoiled by having to fly the aircraft. Nothing was gained, therefore, and firing was reduced to single shots.
We used to say ironically that we only had to shatter the morale of the bomber crew by a few artillery shots, then we could ram the Mustangs and Thunderbolts with our gun barrel. From
The First and the Last by Adolf Galland.
Sounds like a superb weapon, eh?