ORIGINAL: el cid again
You may not do this for super heasvy guns - we tried - but the effect values are too high - if they work for surface combat they kill way too many planes. These weapons were used - but not with effect - there is no know instance where they caused a kill or damage - and while probably it happened - it should be very low in effect - and our system here won't let us do that unless we made the device ineffective for surface combat.
An interesting tidbit I found in "SMALL ARMS, ARTILLERY AND SPECIAL WEAPONS OF THE THIRD REICH - AN ENCYCLOPEDIC SURVEY" by Terry Gander and Peter Chamberlain states that the 305 mm guns om Helgoland had their mountings modified for a maximum elevation of 70 degrees and that they were used at long range against bomber "boxes". They are said to have achieved "kills", e.g four on January 4th, 1944. I don't know if this story isn't anecdotal - never heard of it before.
In the same book there is a section about a Skoda project for a 240 mm AA gun for the Navy. Intended for coastal installations, it was a twin turret weighing 600 tons with barrels 79,4 calibres long, a maximum elevation of 90 degrees, firing 205 kg shells at a rate of eight per minute to a ceiling of about 36.000 m (roughly 120.000 feet) and a maximum range of 48.000 m (about 52.500 yds). Design work apparently dropped after 1942. They also say that the barrels would probably have been "shot out" after a single day's use.
