So I'm listening to Dan Carlin's Blueprint for Armageddon VI podcast and he's talking about the shelling of Paris in 1918 by the huge German Paris guns. He claims that the guns could fire up to 81 (!!!) miles while the 16 inch guns on an Iowa class battleship could fire up to about 30. He also claims that the German gunners had to take the rotation of the earth into account in their firing calculations. Not that I'd expect Carlin to intentionally disseminate incorrect info, but is this true? If so, how and why did the Germans build such ridiculously powerful guns while no one else did so?
From a technical standpoint they were quite the achievement, surpassing anything made at the time. But as a weapon of war they were nearly useless. They were so inaccurate that they could not be used against military targets. Even when fired at cities as large as Paris they would miss as often as they hit. Shortly after the war the French built an equivalent weapon but never produced many because it isn't that useful. The gun gets its extreme range by launching the shells quite high into the atmosphere where they cruise along in the low pressure. This also causes their extreme inaccuracy.
The Paris-Guns succeeded as propaganda weapons, but they only worked as such for a short while. Initially the French were demoralized that Paris was being shelled by an unstoppable weapon, but when people realized how inaccurate and weak the shells were the panic passed. Continuing to use them after that point was pretty much a waste of time and resources.
Comparing the Paris-Gun and a battleship cannon isn't really a fair comparison, the two weapons are built for different jobs. A battleship like the Iowa has cannons designed to destroy other battleships and to bombard land based fortifications. In theory you could mount a weapon like the Paris-Gun on a battleship, but it wouldn't serve any useful function; though, it might be easier to aim by steering the ship. You'd never hit another ship with it (much less a fortification), and it would be too slow to reload and too fast to deteriorate to be useful to support land operations.
So it was pretty neat as a technical achievement, but overall useless outside a small window of time as a weapon of terror.
They were a logistical nightmare: maintenance heavy and the barrel wear was extreme. Every shell was machined with a progressively larger diameter to counter the barrel wear and if you dropped them in in the wrong order, oops. Since you're comparing with the Iowas, an Iowa 16"/50 rifle fires 2 rounds/min with a 40lb explosive charge. The Paris Gun fires 20 rounds/day with a 7lb explosive charge. When you are putting that on a city sized target, the cost for effect value proposition really isn't there.
Also, the coriolis effect is not a big deal. Even snipers have to contend with it at ranges less than a kilometer.