At first this may seem to be an easy question. But I still wonder. The Paris Gun's carriage was a railway gun design. Its components were transported by rail, but it had to be emplaced and assembled before firing. The gun did not fire directly from rails, but rather was mounted on a turntable. Also, I don't think the German designation for the gun described it a railway gun (Eisenbahngeschütz). Thoughts?
Yes, the Paris Gun was often mounted on a railway gun carriage (the same type of carriage used for the Langer Max 38cm guns). However, it was also sometimes mounted on fixed front-pivot type coastal emplacement carriages (usually when being tested in Germany, though I have also seen a photo of it on such a carriage apparently in a forest, which implies it being in an operational situation). It was, as you say, transported by rail and then the carriage was fixed to a turntable for firing - as was the 38-cm Langer Max. As far as I know, however, the Langer Max could also be fired from a railway track, but the Paris Gun was never fired from rails. I've never actually seen the Paris Gun referred to as a railway gun and although it is included in Gerhard Taube's Deutsche Eisenbahn Geschutze and Ian Hogg and John Batchelor's Rail Gun, none of them actually refers to it as a railway gun.
On the whole, I feel that it would be more correct to describe the Paris Gun as a railway-transported gun.
Of course, but the point at issue is was it a railway gun in the sense generally taken of what 'railway gun' means, that is to say, a gun which was fired from its rail mounting? And in the case of the Paris Gun, no it wasn't.
Thanks for the input. The 42cm Gamma Howitzer falls into the same category - a rail transportable gun, but not a railway gun. The discussion brings forward the question of what is a railway gun? The other end of the spectrum are small caliber guns mounted on armored trains which are also not railway guns. So perhaps railway guns are heavy artillery pieces mounted on, transported by, and fired from a railway wagon; although what caliber constitutes a heavy artillery piece is open to debate.
Near enough for me!
For what it's worth, Wiki definition is "A railway gun, also called a railroad gun, is a large artillery piece, often surplus naval ordnance, mounted on, transported by, and fired from a specially designed railway wagon."
My idea of "Large", would be in excess of 6" cailbre.
