It was meant to be used against Leningrad after the capture of Sebastopol in 1942. It was moved to Riga (some say sources it stayed their) and a firing 'platform' was built at Taylsy (some sources say the gun was also transported there and prepared for firing), wherever it may have been exactly....it wasn't used.
In early 1943 the gun went to Rügerswalde for general overhaul and replacing the gun barrel, it fired one last shot there in a demonstration for the Oberkommando der Wehrmacht on 19 may 1943.
In september 1943 it was moved to Auerswalde, just north of Chemnitz, where it remained in a depot until the end of the war.
The gun was destroyed in april 1945 when the Russians were drawing near.